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VCS-256 exam Dumps Source : Administration of Veritas InfoScale Availability 7.1 for UNIX/Linux

Test Code : VCS-256
Test title : Administration of Veritas InfoScale Availability 7.1 for UNIX/Linux
Vendor title : Veritas
: 84 real Questions

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Veritas Administration of Veritas InfoScale

Durham solid brings in president to champion CEO with enlargement | killexams.com real Questions and Pass4sure dumps

No outcome discovered, are trying current keyword!Veritas Collaborative is expected to proclaim the following day that ... Browder received his Bachelor of enterprise Administration in accounting from the university of Georgia’s Terry faculty of company. The ...

Veritas displays information administration Ambitions, Updates NetBackup | killexams.com real Questions and Pass4sure dumps

After being officially spun off from Symantec this yr, Veritas these days revealed that it plans to hub of attention on supplying a sturdy portfolio of suggestions management products and functions with the purpose to span on-premise and cloud deployments.

Doug Matthews, vp of suggestions availability for Veritas, says in foster of the formal spin off, the Veritas enterprise unit went back to the drafting board to design a latest assistance administration platform with the purpose to accomplish wide utilize of metadata to simplify managing the huge quantities of records being allotted throughout deepest and public clouds.

To start to tackle that problem, Veritas released an update to its NetBackup software, which now gives pilot for cloud features from Amazon web capabilities (AWS), Google, Hitachi information techniques (HDS), Verizon and Cloudian, moreover Hewlett Packard. The current version additionally has superior integration with digital computing device software for VMware and Microsoft. NetBackup 7.7 additionally gives better assist for NetApp clustered data ONTAP (cDOT) and Microsoft SQL Server software, together with more desirable self-service capabilities that enable both IT and non-IT users to independently manage and manage backup and recovery.

 

at the core of the Veritas assistance strategy is the edition 5.0 unlock of Veritas records insight, as a course to analyze data stored in dissimilar storage techniques working on premise in addition to on dissimilar cloud storage features offered by course of box. besides monitoring anomalous user activity and conduct, Matthews observed that information insight edition 5.0, due out this summer, will facilitate retention administration and compliance, as well as assist identify sets of information that are most elegant to the firm.

Veritas will likewise address information administration considerations via Veritas InfoScale, a software-defined strategy to managing storage and software availability, and thru Veritas counsel Map, a cloud utility that makes utilize of statistics saved in NetBackup to supply visibility into the status and the course unstructured statistics is kept across the business.

finally, by course of the Veritas Resiliency Platform, which is obtainable now, Veritas is additionally providing a company continuity carrier around its backup and recovery application using a admixture of aboriginal and cloud circumstances of its information coverage software.

within the age of the hybrid cloud, Matthews observed the largest challenge facing IT companies is reconciling the administration of the entire isolated records silos that now exist inside and out of doors of the cloud in ways that consume into account each the risks to the records and the service stage agreements (SLAs) linked to it. though enabling such reconciliation would seemingly consume some variety of information management nirvana, the volume of specific work to eddy that imaginative and prescient into time-honored veracity is incredible. truly, for many groups, it could achieve to subsist more straightforward to simply birth over than to try to lengthen latest statistics management frameworks that were never truly designed to operate at that flush of disbursed scale.


Veritas Enters current government-extensive Cloud information management settlement for the U.S. customary features Administration | killexams.com real Questions and Pass4sure dumps

MOUNTAIN VIEW, Calif., Sept. 12, 2018 /PRNewswire/ -- Veritas technologies, the international market partake chief within the commercial enterprise information insurance policy and software-defined storage market, has entered right into a government-broad contract for the U.S. widely wide-spread functions Administration (GSA) to give federal organizations with data governance and cloud facts management application.

beneath the agreement, government companies could beget entry to Veritas information insurance blueprint and cloud options at negotiated expenses to enable for more suitable facts administration. The agreement is derived from the GSA IT time table 70 and thoroughly supports the Federal suggestions technology Acquisition Reform Act (FITARA) Enhancement program.

The contract brings Veritas' award-winning enterprise records management portfolio to totality eligible federal, state, local and tribal government companies. These corporations can construct upon the records coverage groundwork of Veritas NetBackup and add additional information management capabilities to accelerate their cloud initiatives. probably the most initial offerings include:

  • Veritas data insight helps companies multiply unstructured information governance to reduce costs, risk and achieve compliance via actionable intelligence into statistics possession, utilization and entry controls.
  • Veritas eDiscovery Platform offers governments with the top-quality analysis toolkit for separating principal felony, regulatory and investigative gadgets, revealing context and prioritizing what's most vital, using a solitary utility.
  • Veritas InfoScale helps federal IT groups more advantageous give protection to suggestions and functions throughout actual and virtual infrastructures. InfoScale minimizes downtime by course of offering high availability and disaster healing over any distance for captious enterprise services, including particular person databases, customized purposes and sophisticated multitier functions across physical, virtual and cloud environments.
  • Veritas business Vault, when offered as an respond with a FedRAMP approved software-as-a provider (SaaS) cloud carrier from bluesource (called EV247), frees businesses from the overhead of owning, running or managing e-mail and file archives. The EV247 respond is powered by using the world's main archiving technology from Veritas. it is a cloud platform, utility archiving solution and managed provider multi function.
  • Veritas 360 statistics management provides agencies the capacity to seriously change their information to address the challenges of conclusion-to-end facts management by records visibility, compliance readiness, company continuity, information insurance blueprint and recoverability. It accomplishes totality of these direct while retaining information/workload portability and storage optimization.
  • "The IT schedule 70 FITARA Enhancement application will give executive agencies with enhanced flexibility in getting access to the creative utility solutions they want at a more robust value to taxpayers," mentioned Alan Thomas, GSA Federal Acquisition service (FAS) Commissioner. "proposing these solutions through a executive-vast, enterprise-level contract is a fine course to carve back duplication in their procurement technique."

    "With the upward shove of cybercrime, the introduction of recent data rules, an upturn of data multiply and escalation of digital privateness, federal groups nowadays should subsist organized to accomplish strategic choices round records assortment, facts storage, the region of that facts—and the course it may likewise subsist safeguarded," pointed out Tom Kennedy, vp and common manager, Veritas Public Sector. "as the undisputed chief in statistics coverage and utility-described storage, Veritas is providing govt companies convenient access to options that assist fight these pressures – to consider statistics, preserve it blanketed, enhance records availability, unencumber the vigour of assistance and garner insights to pressure advancements in govt courses." 

    in regards to the IT schedule 70 FITARA Enhancement ProgramThe Federal assistance know-how Acquisition Reform Act (FITARA) is a GSA software designed to accomplish it more convenient and extra in your cost purview for federal corporations to acquire utility. FITARA become passed by means of Congress in 2014 and the workplace of management and finances (OMB) carried out tips in 2016. It goals to reduce fees and bring imaginative know-how to the federal govt.

    About VeritasVeritas technologies is the leader within the global business statistics insurance policy and application-defined storage market. We champion probably the most captious businesses on the earth, including 86 p.c of the international Fortune 500, lower back up and come by well their statistics, hold it cozy and accessible, gape after in opposition t failure and achieve regulatory compliance. As enterprises modernize their IT infrastructure, Veritas delivers the expertise that helps them reduce risks and capitalize on their information. learn extra at www.veritas.com or comply with us on Twitter at @veritastechllc.

    Veritas and the Veritas brand are emblems or registered logos of Veritas applied sciences LLC or its associates in the U.S. and different countries. different names could subsist emblems of their respective homeowners.

    PR Contact

    Veritas TechnologiesDayna Fried +1 925 493 9020dayna.fried@veritas.com

     

    Cision View customary content material to download multimedia:https://www.prnewswire.com/news-releases/veritas-enters-new-govt-wide-cloud-information-management-contract-for-the-us-normal-functions-administration-300710751.html

    source Veritas applied sciences


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    Administration of Veritas InfoScale Availability 7.1 for UNIX/Linux

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    King of the network operating systems | killexams.com real questions and Pass4sure dumps

    COMPUTINGFrom...Network World Fusion networking

    January 24, 2000Web posted at: 12:11 p.m. EST (1711 GMT)

    by John Bass and James Robinson, Network World Test Alliance

    (IDG) -- It totality boils down to what you're looking for in a network operating system (NOS).

    Do you want it spare and springy so you can install it any course you please? Perhaps administration bells and management whistles are what you need so you can deploy several hundred servers. Or maybe you want an operating system that's robust enough so that you sleep fancy a baby at night?

    The proper intelligence is that there is a NOS waiting just for you. After the rash of recent software revisions, they took an in-depth gape at four of the major NOSes on the market: Microsoft's Windows 2000 Advanced Server, Novell's NetWare 5.1, Red Hat Software's Linux 6.1 and The Santa Cruz Operation's (SCO) UnixWare 7.1.1. Sun declined their invitation to submit Solaris because the company says it's working on a current version.

    Microsoft's Windows 2000 edges out NetWare for the Network World Blue Ribbon Award. Windows 2000 tops the territory with its management interface, server monitoring tools, storage management facilities and security measures.

    However, if it's performance you're after, no product came near to Novell's NetWare 5.1's numbers in their exhaustive file service and network benchmarks. With its lightning-fast engine and Novell's directory-based administration, NetWare offers a much foundation for an enterprise network.

    We institute the latest release of Red Hat's commercial Linux bundle led the list for flexibility because its modular design lets you pare down the operating system to suit the chore at hand. Additionally, you can create scripts out of multiple Linux commands to automate tasks across a distributed environment.

    While SCO's UnixWare seemed to lag behind the pack in terms of file service performance and NOS-based administration features, its scalability features accomplish it a stalwart candidate for running enterprise applications.

    The numbers are in

    Regardless of the job you saddle your server with, it has to fulfill well at reading and writing files and sending them across the network. They designed two benchmark suites to measure each NOS in these two categories. To reflect the real world, their benchmark tests consider a wide purview of server conditions.

    NetWare was the hands-down leader in their performance benchmarking, taking first status in two-thirds of the file tests and earning top billing in the network tests.

    Red Hat Linux followed NetWare in file performance overall and even outpaced the leader in file tests where the read/write loads were small. However, Linux did not fulfill well handling big loads - those tests in which there were more than 100 users. Under heavier user loads, Linux had a current to halt servicing file requests for a short period and then start up again.

    Windows 2000 demonstrated destitute write performance across totality their file tests. In fact, they institute that its write performance was about 10% of its read performance. After consulting with both Microsoft and Client/Server Solutions, the author of the Benchmark Factory testing implement they used, they determined that the destitute write performance could subsist due to two factors. One, which they were unable to verify, might subsist a practicable performance problem with the SCSI driver for the hardware they used.

    More significant, though, was an issue with their test software. Benchmark Factory sends a write-through flag in each of its write requests that is suppositious to antecedent the server to update cache, if appropriate, and then constrain a write to disk. When the write to disk occurs, the write call is released and the next request can subsist sent.

    At first glance, it appeared as if Windows 2000 was the only operating system to veneration this write-through flag because its write performance was so poor. Therefore, they ran a second round of write tests with the flag turned off.

    With the flag turned off, NetWare's write performance increased by 30%. This test proved that Novell does indeed veneration the write-through flag and will write to disk for each write request when that flag is set. But when the write-through flag is disabled, NetWare writes to disk in a more efficient manner by batching together contiguous blocks of data on the cache and writing totality those blocks to disk at once.

    Likewise, Red Hat Linux's performance increased by 10% to 15% when the write-through flag was turned off. When they examined the Samba file system code, they institute that it too honors the write-through flag. The Samba code then finds an optimum time during the read/write sequence to write to disk.

    This second round of file testing proves that Windows 2000 is conditional on its file system cache to optimize write performance. The results of the testing with the write-through flag off were much higher - as much as 20 times faster. However, Windows 2000 still fell behind both NetWare and RedHat Linux in the file write tests when the write-through flag was off.

    SCO honors the write-through flag by default, since its journaling file system is constructed to maximize data integrity by writing to disk for totality write requests. The results in the write tests with the write-through flag on were very similar to the test results with the write-through flag turned off.

    For the network benchmark, they developed two tests. Their long TCP transaction test measured the bandwidth each server can sustain, while their short TCP transaction test measured each server's skill to handle big numbers of network sessions with little file transactions.

    Despite a destitute showing in the file benchmark, Windows 2000 came out on top in the long TCP transaction test. Windows 2000 is the only NOS with a multithreaded IP stack, which allows it to handle network requests with multiple processors. Novell and Red Hat whine they are working on integrating this capability into their products.

    NetWare and Linux likewise registered stalwart long TCP test results, coming in second and third, respectively.

    In the short TCP transaction test, NetWare came out the clear winner. Linux earned second status in spite of its want of champion for abortive TCP closes, a course by which an operating system can quickly rend down TCP connections. Their testing software, Ganymede Software's Chariot, uses abortive closes in its TCP tests.

    Moving into management

    As enterprise networks grow to require more servers and champion more halt users, NOS management tools become crucial elements in keeping networks under control. They looked at the management interfaces of each product and drilled down into how each handled server monitoring, client administration, file and print management, and storage management.

    We institute Windows 2000 and NetWare provide equally useful management interfaces.

    Microsoft Management Console (MMC) is the glue that holds most of the Windows 2000 management functionality together. This configurable graphical user interface (GUI) lets you snap in Microsoft and third-party applets that customize its functionality. It's a two-paned interface, much fancy Windows Explorer, with a nested list on the left and selection details on the right. The console is facile to utilize and lets you configure many local server elements, including users, disks, and system settings such as time and date.

    MMC likewise lets you implement management policies for groups of users and computers using energetic Directory, Microsoft's current directory service. From the energetic Directory management implement inside MMC, you can configure users and change policies.

    The network configuration tools are institute in a sever application that opens when you click on the Network Places icon on the desktop. Each network interface is listed inside this window. You can add and change protocols and configure, enable and disable interfaces from here without rebooting.

    NetWare offers several interfaces for server configuration and management. These tools tender duplicate functionality, but each is useful depending from where you are trying to manage the system. The System Console offers a number of tools for server configuration. One of the most useful is NWConfig, which lets you change start-up files, install system modules and configure the storage subsystem. NWConfig is simple, intuitive and predictable.

    ConsoleOne is a Java-based interface with a few graphical tools for managing and configuring NetWare. Third-party administration tools can plug into ConsoleOne and let you manage multiple services. They deem ConsoleOne's interface is a bit unsophisticated, but it works well enough for those who must beget a Windows- based manager.

    Novell likewise offers a Web-accessible management application called NetWare Management Portal, which lets you manage NetWare servers remotely from a browser, and NWAdmin32, a relatively simple client-side implement for administering Novell Directory Services (NDS) from a Windows 95, 98 or NT client.

    Red Hat's overall systems management interface is called LinuxConf and can elope as a graphical or text-based application. The graphical interface, which resembles that of MMC, works well but has some layout issues that accomplish it difficult to utilize at times. For example, when you elope a setup application that takes up a lot of the screen, the system resizes the application larger than the desktop size.

    Still, you can manage pretty much anything on the server from LinuxConf, and you can utilize it locally or remotely over the Web or via telnet. You can configure system parameters such as network addresses; file system settings and user accounts; and set up add-on services such as Samba - which is a service that lets Windows clients come by to files residing on a Linux server - and FTP and Web servers. You can apply changes without rebooting the system.

    Overall, Red Hat's interface is useful and the underlying tools are powerful and flexible, but LinuxConf lacks the polish of the other vendors' tools.

    SCO Admin is a GUI-based front halt for about 50 SCO UnixWare configuration and management tools in one window. When you click on a tool, it brings up the application to manage that particular in a sever window.

    Some of SCO's tools are GUI-based while others are text-based. The server required a reboot to apply many of the changes. On the plus side, you can manage multiple UnixWare servers from SCOAdmin.

    SCO likewise offers a useful Java-based remote administration implement called WebTop that works from your browser.

    An eye on the servers and clients

    One captious administration chore is monitoring the server itself. Microsoft leads the pack in how well you can maintain an eye on your server's internals.

    The Windows 2000 System Monitor lets you view a real-time, running graph of system operations, such as CPU and network utilization, and memory and disk usage. They used these tools extensively to determine the outcome of their benchmark tests on the operating system. Another implement called Network Monitor has a basic network packet analyzer that lets you note the types of packets coming into the server. Together, these Microsoft utilities can subsist used to compare performance and capacity across multiple Windows 2000 servers.

    NetWare's Monitor utility displays processor utilization, memory usage and buffer utilization on a local server. If you know what to gape for, it can subsist a powerful implement for diagnosing bottlenecks in the system. Learning the signification of each of the monitored parameters is a bit of a challenge, though.

    If you want to gape at performance statistics across multiple servers, you can tap into Novell's Web Management Portal.

    Red Hat offers the touchstone Linux command-line tools for monitoring the server, such as iostat and vmstat. It has no graphical monitoring tools.

    As with any Unix operating system, you can write scripts to automate these tools across Linux servers. However, these tools are typically cryptic and require a high flush of proficiency to utilize effectively. A suite of graphical monitoring tools would subsist a much addition to Red Hat's Linux distribution.

    UnixWare likewise offers a number of monitoring tools. System Monitor is UnixWare's simple but limited GUI for monitoring processor and memory utilization. The sar and rtpm command-line tools together list real-time system utilization of buffer, CPUs and disks. Together, these tools give you a proper overall concept of the load on the server.

    Client administration

    Along with managing the server, you must manage its users. It's no amaze that the two NOSes that ship with an integrated directory service topped the territory in client administration tools.

    We were able to configure user permissions via Microsoft's energetic Directory and the directory administration implement in MMC. You can group users and computers into organizational units and apply policies to them.

    You can manage Novell's NDS and NetWare clients with ConsoleOne, NWAdmin or NetWare Management Portal. Each can create users, manage file space, and set permissions and rights. Additionally, NetWare ships with a five-user version of Novell's ZENworks tool, which offers desktop administration services such as hardware and software inventory, software distribution and remote control services.

    Red Hat Linux doesn't tender much in the course of client administration features. You must control local users through Unix consent configuration mechanisms.

    UnixWare is similar to Red Hat Linux in terms of client administration, but SCO provides some Windows binaries on the server to remotely set file and directory permissions from a Windows client, as well as create and change users and their settings. SCO and Red Hat tender champion for the Unix-based Network Information Service (NIS). NIS is a store for network information fancy logon names, passwords and home directories. This integration helps with client administration.

    Handling the staples: File and print

    A NOS is nothing without the skill to partake file storage and printers. Novell and Microsoft collected top honors in these areas.

    You can easily add and maintain printers in Windows 2000 using the print administration wizard, and you can add file shares using energetic Directory management tools. Windows 2000 likewise offers Distributed File Services, which let you combine files on more than one server into a solitary share.

    Novell Distributed Print Services (NDPS) let you quickly incorporate printers into the network. When NDPS senses a current printer on the network, it defines a Printer Agent that runs on the printer and communicates with NDS. You then utilize NDS to define the policies for the current printer.

    You define NetWare file services by creating and then mounting a disk volume, which likewise manages volume policies.

    Red Hat includes Linux's printtool utility for setting up server-connected and networks printers. You can likewise utilize this GUI to create printcap entries to define printer access.

    Linux has a set of command-line file system configuration tools for mounting and unmounting partitions. Samba ships with the product and provides some integration for Windows clients. You can configure Samba only through a cryptic configuration ASCII file - a sedate drawback.

    UnixWare provides a springy GUI-based printer setup implement called Printer SetUp Manager. For file and volume management, SCO offers a implement called VisionFS for interoperability with Windows clients. They used VisionFS to allow their NT clients to access the UnixWare server. This service was facile to configure and use.

    Storage management

    Windows 2000 provides the best tools for storage management. Its graphical Manage Disks implement for local disk configuration includes software RAID management; you can dynamically add disks to a volume set without having to reboot the system. Additionally, a signature is written to each of the disks in an array so that they can subsist moved to another 2000 server without having to configure the volume on the current server. The current server recognizes the drives as members of a RAID set and adds the volume to the file system dynamically.

    NetWare's volume management tool, NWConfig, is facile to use, but it can subsist a minute confusing to set up a RAID volume. Once they knew what they were doing, they had no problems formatting drives and creating a RAID volume. The implement looks a minute primitive, but they give it high marks for functionality and ease of use.

    Red Hat Linux offers no graphical RAID configuration tools, but its command line tools made RAID configuration easy.

    To configure disks on the UnixWare server, they used the Veritas Volume Manager graphical disk and volume administration implement that ships with UnixWare. They had some problems initially getting the implement to recognize the drives so they could subsist formatted. They managed to work around the disk configuration problem using an assortment of command line tools, after which Volume Manager worked well.

    Security

    While they did not probe these NOSes extensively to expose any security weaknesses, they did gape at what they offered in security features.

    Microsoft has made significant strides with Windows 2000 security. Windows 2000 supports Kerberos public key certificates as its primary authentication mechanism within a domain, and allows additional authentication with smart cards. Microsoft provides a Security Configuration implement that integrates with MMC for facile management of security objects in the energetic Directory Services system, and a current Encrypting File System that lets you designate volumes on which files are automatically stored using encryption.

    Novell added champion for a public-key infrastructure into NetWare 5 using a public certificate schema developed by RSA Security that lets you tap into NDS to generate certificates.

    Red Hat offers a basic Kerberos authentication mechanism. With Red Hat Linux, as with most Unix operating systems, the network services can subsist individually controlled to multiply security. Red Hat offers Pluggable Authentication Modules as a course of allowing you to set authentication policies across programs running on the server. Passwords are protected with a shadow file. Red Hat likewise bundles firewall and VPN services.

    UnixWare has a set of security tools called Security Manager that lets you set up varying degrees of intrusion protection across your network services, from no restriction to turning totality network services off. It's a proper management time saver, though you could manually modify the services to achieve the selfsame result.

    Stability and foible tolerance

    The most feature-rich NOS is of minute value if it can't maintain a server up and running. Windows 2000 offers software RAID 0, 1 and 5 configurations to provide foible tolerance for onboard disk drives, and has a built-in network load-balancing feature that allows a group of servers to gape fancy one server and partake the selfsame network title and IP address. The group decides which server will service each request. This not only distributes the network load across several servers, it likewise provides foible tolerance in case a server goes down. On a lesser scale, you can utilize Microsoft's Failover Clustering to provide basic failover services between two servers.

    As with NT 4.0, Windows 2000 provides memory protection, which means that each process runs in its own segment.

    There are likewise backup and restore capabilities bundled with Windows 2000.

    Novell has an add-on product for NetWare called Novell Cluster Services that allows you to cluster as many as eight servers, totality managed from one location using ConsoleOne, NetWare Management Portal or NWAdmin32. But Novell presently offers no clustering products to provide load balancing for applications or file services. NetWare has an elaborate memory protection scheme to segregate the memory used for the kernel and applications, and a Storage Management Services module to provide a highly springy backup and restore facility. Backups can subsist all-inclusive, cover parts of a volume or store a differential snapshot.

    Red Hat provides a load-balancing product called piranha with its Linux. This package provides TCP load balancing between servers in a cluster. There is no hard circumscribe to the number of servers you can configure in a cluster. Red Hat Linux likewise provides software RAID champion through command line tools, has memory protection capabilities and provides a rudimentary backup facility.

    SCO provides an optional feature to cluster several servers in a load-balancing environment with Non-Stop Clustering for a high flush of fault-tolerance. Currently, Non-Stop Clustering supports six servers in a cluster. UnixWare provides software RAID champion that is managed using SCO's On-Line Data Manager feature. totality the touchstone RAID levels are supported. Computer Associates' bundled ArcServeIT 6.6 provides backup and restore capabilities. UnixWare has memory protection capabilities.

    Documentation

    Because their testing was conducted before Windows 2000's generic availability ship date, they were not able to evaluate its hard-copy documentation. The online documentation provided on a CD is extensive, useful and well-organized, although a Web interface would subsist much easier to utilize if it gave more than a pair of sentences at a time for a particular assist topic.

    NetWare 5 comes with two manuals: a minute manual for installing and configuring the NOS with proper explanations of concepts and features along with an overview of how to configure them, and a little spiral-bound booklet of quick start cards. Novell's online documentation is very helpful.

    Red Hat Linux comes with three manuals - an installation guide, a getting started pilot and a reference manual - totality of which are facile to follow.

    Despite being the most difficult product to install, UnixWare offers the best documentation. It comes with two manuals: a system handbook and a getting started guide. The system handbook is a reference for conducting the installation of the operating system. It does a proper job of reflecting this painful experience. The getting started pilot is well-written and well-organized. It covers many of the tools needed to configure and maintain the operating system. SCO's online documentation looks nice and is facile to follow.

    Wrapping up

    The bottom line is that these NOSes tender a wide purview of characteristics and provide enterprise customers with a much deal of option regarding how each can subsist used in any given corporate network.

    If you want a good, generic purpose NOS that can deliver enterprise-class services with totality the bells and whistles imaginable, then Windows 2000 is the strongest contender. However, for high performance, enterprise file and print services, their tests flaunt that Novell leads the pack. If you're willing to pay a higher cost for scalability and reliability, SCO UnixWare would subsist a safe bet. But if you need an inexpensive alternative that will give you bare-bones network services with decent performance, Red Hat Linux can certainly fit the bill.

    The option is yours.

    Bass is the technical director and Robinson is a senior technical staff member at Centennial Networking Labs (CNL) at North Carolina status University in Raleigh. CNL focuses on performance, capacity and features of networking and server technologies and equipment.

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    Debate will focus on Linux vs. LinuxJanuary 20, 2000Some Windows 2000 PCs will jump the gunJanuary 19, 2000IBM throws Linux lovefestJanuary 19, 2000Corel Linux will elope Windows appsJanuary 10, 2000Novell's eDirectory spans platformsNovember 16, 1999New NetWare embraces Web appsNovember 2, 1999Microsoft sets a date for Windows 2000October 28, 1999

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    Fusion's Forum: Square off with the vendors over who has the best NOS(Network World Fusion)How they did it: Details of the testing(Network World Fusion)Find out the tuning parameters(Network World Fusion)Download the Config files(Network World Fusion)The Shootout results(Network World Fusion)Fusion's NOS resources(Network World Fusion)With Windows 2000, NT grows up(Network World Fusion)Fireworks expected at NOS showdown(Network World Fusion)

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    King of the NOS Hill: Windows 2000 Reigns Supreme | killexams.com real questions and Pass4sure dumps

    It totality boils down to what you're looking for in a network operating system (NOS).

    Do you want it spare and springy so you can install it any course you please?

    Perhaps administration bells and management whistles are what you need so you can deploy several hundred servers. Or maybe you want an operating system that's robust enough so that you sleep fancy a baby at night?

    The proper intelligence is that there is a NOS waiting just for you. After the rash of recent software revisions, they took an in-depth gape at four of the major NOSes on the market: Microsoft's Windows 2000 Advanced Server, Novell's NetWare 5.1, Red Hat Software's Linux 6.1 and The Santa Cruz Operation's (SCO) UnixWare 7.1.1. Sun declined their invitation to submit Solaris because the company says it's working on a current version.

    Microsoft's Windows 2000 edges out NetWare for the Network World Blue Ribbon Award. Windows 2000 tops the territory with its management interface, server monitoring tools, storage management facilities and security measures.

    However, if it's performance you're after, no product came near to Novell's NetWare 5.1's numbers in their exhaustive file service and network benchmarks.

    With its lightning-fast engine and Novell's directory-based administration, NetWare offers a much foundation for an enterprise network.

    We institute the latest release of Red Hat's commercial Linux bundle led the list for flexibility because its modular design lets you pare down the operating system to suit the chore at hand. Additionally, you can create scripts out of multiple Linux commands to automate tasks across a distributed environment.

    While SCO's UnixWare seemed to lag behind the pack in terms of file service performance and NOS-based administration features, its scalability features accomplish it a stalwart candidate for running enterprise applications.

    Regardless of the job you saddle your server with, it has to fulfill well at reading and writing files and sending them across the network. They designed two benchmark suites to measure each NOS in these two categories. To reflect the real world, their benchmark tests consider a wide purview of server conditions.

    NetWare was the hands-down leader in their performance benchmarking, taking first status in two-thirds of the file tests and earning top billing in the network tests.

    Red Hat Linux followed NetWare in file performance overall and even outpaced the leader in file tests where the read/write loads were small. However, Linux did not fulfill well handling big loads - those tests in which there were more than 100 users. Under heavier user loads, Linux had a current to halt servicing file requests for a short period and then start up again.

    Windows 2000 demonstrated destitute write performance across totality their file tests. In fact, they institute that its write performance was about 10 percent of its read performance. After consulting with both Microsoft and Client/Server Solutions, the author of the Benchmark Factory testing implement they used, they determined that the destitute write performance could subsist due to two factors. One, which they were unable to verify, might subsist a practicable performance problem with the SCSI driver for the hardware they used.

    More significant, though, was an issue with their test software. Benchmark Factory sends a write-through flag in each of its write requests that is suppositious to antecedent the server to update cache, if appropriate, and then constrain a write to disk. When the write to disk occurs, the write call is released and the next request can subsist sent.

    At first glance, it appeared as if Windows 2000 was the only operating system to veneration this write-through flag because its write performance was so poor.

    Therefore, they ran a second round of write tests with the flag turned off.

    With the flag turned off, NetWare's write performance increased by 30 percent.

    This test proved that Novell does indeed veneration the write through flag and will write to disk for each write request when that flag is set. But when the write through flag is disabled, NetWare writes to disk in a more efficient manner by batching together contiguous blocks of data on the cache and writing totality those blocks to disk at once.

    Likewise, Red Hat Linux's performance increased by 10 percent to 15 percent when the write through flag was turned off. When they examined the Samba file system code, they institute that it too honors the write through flag. The Samba code then finds an optimum time during the read/write sequence to write to disk.

    This second round of file testing proves that Windows 2000 is conditional on its file system cache to optimize write performance. The results of the testing with the write through flag off were much higher - as much as 20 times faster.

    However, Windows 2000 still fell behind both NetWare and RedHat Linux in the file write tests when the write through flag was off.

    SCO honors the write through flag by default, since its journaling file system is constructed to maximize data integrity by writing to disk for totality write requests. The results in the write tests with the write through flag on were very similar to the test results with the write through flag turned off.

    For the network benchmark, they developed two tests. Their long TCP transaction test measured the bandwidth each server can sustain, while their short TCP transaction test measured each server's skill to handle big numbers of network sessions with little file transactions.

    Despite a destitute showing in the file benchmark, Windows 2000 came out on top in the long TCP transaction test. Windows 2000 is the only NOS with a multithreaded IP stack, which allows it to handle network requests with multiple processors. Novell and Red Hat whine they are working on integrating this capability into their products.

    NetWare and Linux likewise registered stalwart long TCP test results, coming in second and third, respectively.

    In the short TCP transaction test, NetWare came out the clear winner. Linux earned second status in spite of its want of champion for abortive TCP closes, a course by which an operating system can quickly rend down TCP connections. Their testing software, Ganymede Software's Chariot, uses abortive closes in its TCP tests.

    As enterprise networks grow to require more servers and champion more halt users, NOS management tools become crucial elements in keeping networks under control.

    We looked at the management interfaces of each product and drilled down into how each handled server monitoring, client administration, file and print management, and storage management.

    We institute Windows 2000 and NetWare provide equally useful management interfaces.

    Microsoft Management Console (MMC) is the glue that holds most of the Windows 2000 management functionality together. This configurable graphical user interface (GUI) lets you snap in Microsoft and third-party applets that customize its functionality. It's a two-paned interface, much fancy Windows Explorer, with a nested list on the left and selection details on the right.

    The console is facile to utilize and lets you configure many local server elements, including users, disks, and system settings such as time and date.

    MMC likewise lets you implement management policies for groups of users and computers using energetic Directory, Microsoft's current directory service. From the energetic Directory management implement inside MMC, you can configure users and change policies.

    The network configuration tools are institute in a sever application that opens when you click on the Network Places icon on the desktop. Each network interface is listed inside this window. You can add and change protocols and configure, enable and disable interfaces from here without rebooting.

    NetWare offers several interfaces for server configuration and management.

    These tools tender duplicate functionality, but each is useful depending from where you are trying to manage the system. The System Console offers a number of tools for server configuration. One of the most useful is NWConfig, which lets you change start-up files, install system modules and configure the storage subsystem. NWConfig is simple, intuitive and predictable.

    ConsoleOne is a Java-based interface with a few graphical tools for managing and configuring NetWare. Third-party administration tools can plug into ConsoleOne and let you manage multiple services. They deem ConsoleOne's interface is a bit unsophisticated, but it works well enough for those who must beget a Windows- based manager.

    Novell likewise offers a Web-accessible management application called NetWare Management Portal, which lets you manage NetWare servers remotely from a browser, and NWAdmin32, a relatively simple client-side implement for administering Novell Directory Services (NDS) from a Windows 95, 98 or NT client.

    Red Hat's overall systems management interface is called LinuxConf and can elope as a graphical or text-based application. The graphical interface, which resembles that of MMC, works well but has some layout issues that accomplish it difficult to utilize at times. For example, when you elope a setup application that takes up a lot of the screen, the system resizes the application larger than the desktop size.

    Still, you can manage pretty much anything on the server from LinuxConf, and you can utilize it locally or remotely over the Web or via telnet. You can configure system parameters such as network addresses; file system settings and user accounts; and set up add-on services such as Samba - which is a service that lets Windows clients come by to files residing on a Linux server - and FTP and Web servers. You can apply changes without rebooting the system.

    Overall, Red Hat's interface is useful and the underlying tools are powerful and flexible, but LinuxConf lacks the polish of the other vendors' tools.

    SCO Admin is a GUI-based front halt for about 50 SCO UnixWare configuration and management tools in one window. When you click on a tool, it brings up the application to manage that particular in a sever window.

    Some of SCO's tools are GUI-based while others are text-based. The server required a reboot to apply many of the changes. On the plus side, you can manage multiple UnixWare servers from SCOAdmin.

    SCO likewise offers a useful Java-based remote administration implement called WebTop that works from your browser.

    One captious administration chore is monitoring the server itself. Microsoft leads the pack in how well you can maintain an eye on your server's internals.

    The Windows 2000 System Monitor lets you view a real-time, running graph of system operations, such as CPU and network utilization, and memory and disk usage. They used these tools extensively to determine the outcome of their benchmark tests on the operating system. Another implement called Network Monitor has a basic network packet analyzer that lets you note the types of packets coming into the server. Together, these Microsoft utilities can subsist used to compare performance and capacity across multiple Windows 2000 servers.

    NetWare's Monitor utility displays processor utilization, memory usage and buffer utilization on a local server. If you know what to gape for, it can subsist a powerful implement for diagnosing bottlenecks in the system. Learning the signification of each of the monitored parameters is a bit of a challenge, though.

    If you want to gape at performance statistics across multiple servers, you can tap into Novell's Web Management Portal.

    Red Hat offers the touchstone Linux command-line tools for monitoring the server, such as iostat and vmstat. It has no graphical monitoring tools.

    As with any Unix operating system, you can write scripts to automate these tools across Linux servers. However, these tools are typically cryptic and require a high flush of proficiency to utilize effectively. A suite of graphical monitoring tools would subsist a much addition to Red Hat's Linux distribution.

    UnixWare likewise offers a number of monitoring tools. System Monitor is UnixWare's simple but limited GUI for monitoring processor and memory utilization. The sar and rtpm command-line tools together list real-time system utilization of buffer, CPUs and disks. Together, these tools give you a proper overall concept of the load on the server.

    Along with managing the server, you must manage its users. It's no amaze that the two NOSes that ship with an integrated directory service topped the territory in client administration tools.

    We were able to configure user permissions via Microsoft's energetic Directory and the directory administration implement in MMC. You can group users and computers into organizational units and apply policies to them.

    You can manage Novell's NDS and NetWare clients with ConsoleOne, NWAdmin or NetWare Management Portal. Each can create users, manage file space, and set permissions and rights. Additionally, NetWare ships with a five-user version of Novell's ZENworks tool, which offers desktop administration services such as hardware and software inventory, software distribution and remote control services.

    Red Hat Linux doesn't tender much in the course of client administration features.

    You must control local users through Unix consent configuration mechanisms.

    UnixWare is similar to Red Hat Linux in terms of client administration, but SCO provides some Windows binaries on the server to remotely set file and directory permissions from a Windows client, as well as create and change users and their settings. SCO and Red Hat tender champion for the Unix-based Network Information Service (NIS). NIS is a store for network information fancy logon names, passwords and home directories. This integration helps with client administration.

    A NOS is nothing without the skill to partake file storage and printers. Novell and Microsoft collected top honors in these areas.

    You can easily add and maintain printers in Windows 2000 using the print administration wizard, and you can add file shares using energetic Directory management tools. Windows 2000 likewise offers Distributed File Services, which let you combine files on more than one server into a solitary share.

    Novell Distributed Print Services (NDPS) let you quickly incorporate printers into the network. When NDPS senses a current printer on the network, it defines a Printer Agent that runs on the printer and communicates with NDS. You then utilize NDS to define the policies for the current printer.

    You define NetWare file services by creating and then mounting a disk volume, which likewise manages volume policies.

    Red Hat includes Linux's print implement utility for setting up server-connected and networks printers. You can likewise utilize this GUI to create printcap entries to define printer access.

    Linux has a set of command-line file system configuration tools for mounting and unmounting partitions. Samba ships with the product and provides some integration for Windows clients. You can configure Samba only through a cryptic configuration ASCII file - a sedate drawback.

    UnixWare provides a springy GUI-based printer setup implement called Printer SetUp Manager. For file and volume management, SCO offers a implement called VisionFS for interoperability with Windows clients. They used VisionFS to allow their NT clients to access the UnixWare server. This service was facile to configure and use.

    Windows 2000 provides the best tools for storage management. Its graphical Manage Disks implement for local disk configuration includes software RAID management; you can dynamically add disks to a volume set without having to reboot the system. Additionally, a signature is written to each of the disks in an array so that they can subsist moved to another 2000 server without having to configure the volume on the current server. The current server recognizes the drives as members of a RAID set and adds the volume to the file system dynamically.

    NetWare's volume management tool, NWConfig, is facile to use, but it can subsist a minute confusing to set up a RAID volume. Once they knew what they were doing, they had no problems formatting drives and creating a RAID volume. The implement looks a minute primitive, but they give it high marks for functionality and ease of use.

    Red Hat Linux offers no graphical RAID configuration tools, but its command line tools made RAID configuration easy.

    To configure disks on the UnixWare server, they used the Veritas Volume Manager graphical disk and volume administration implement that ships with UnixWare. They had some problems initially getting the implement to recognize the drives so they could subsist formatted. They managed to work around the disk configuration problem using an assortment of command line tools, after which Volume Manager worked well.

    While they did not probe these NOSes extensively to expose any security weaknesses, they did gape at what they offered in security features.

    Microsoft has made significant strides with Windows 2000 security. Windows 2000 supports Kerberos public key certificates as its primary authentication mechanism within a domain, and allows additional authentication with smart cards. Microsoft provides a Security Configuration implement that integrates with MMC for facile management of security objects in the energetic Directory Services system, and a current Encrypting File System that lets you designate volumes on which files are automatically stored using encryption.

    Novell added champion for a public-key infrastructure into NetWare 5 using a public certificate schema developed by RSA Security that lets you tap into NDS to generate certificates.

    Red Hat offers a basic Kerberos authentication mechanism. With Red Hat Linux, as with most Unix operating systems, the network services can subsist individually controlled to multiply security. Red Hat offers Pluggable Authentication Modules as a course of allowing you to set authentication policies across programs running on the server. Passwords are protected with a shadow file. Red Hat likewise bundles firewall and VPN services.

    UnixWare has a set of security tools called Security Manager that lets you set up varying degrees of intrusion protection across your network services, from no restriction to turning totality network services off. It's a proper management time saver, though you could manually modify the services to achieve the selfsame result.

    The most feature-rich NOS is of minute value if it can't maintain a server up and running. Windows 2000 offers software RAID 0, 1 and 5 configurations to provide foible tolerance for onboard disk drives, and has a built-in network load-balancing feature that allows a group of servers to gape fancy one server and partake the selfsame network title and IP address. The group decides which server will service each request. This not only distributes the network load across several servers, it likewise provides foible tolerance in case a server goes down.

    On a lesser scale, you can utilize Microsoft's Failover Clustering to provide basic failover services between two servers.

    As with NT 4.0, Windows 2000 provides memory protection, which means that each process runs in its own segment.

    There are likewise backup and restore capabilities bundled with Windows 2000.

    Novell has an add-on product for NetWare called Novell Cluster Services that allows you to cluster as many as eight servers, totality managed from one location using ConsoleOne, NetWare Management Portal or NWAdmin32. But Novell presently offers no clustering products to provide load balancing for applications or file services. NetWare has an elaborate memory protection scheme to segregate the memory used for the kernel and applications, and a Storage Management Services module to provide a highly springy backup and restore facility.

    Backups can subsist all-inclusive, cover parts of a volume or store a differential snapshot.

    Red Hat provides a load-balancing product called piranha with its Linux. This package provides TCP load balancing between servers in a cluster. There is no hard circumscribe to the number of servers you can configure in a cluster. Red Hat Linux likewise provides software RAID champion through command line tools, has memory protection capabilities and provides a rudimentary backup facility.

    SCO provides an optional feature to cluster several servers in a load-balancing environment with Non-Stop Clustering for a high flush of fault-tolerance.

    Currently, Non-Stop Clustering supports six servers in a cluster. UnixWare provides software RAID champion that is managed using SCO's On-Line Data Manager feature. totality the touchstone RAID levels are supported. Computer Associates' bundled ArcServeIT 6.6 provides backup and restore capabilities. UnixWare has memory protection capabilities.

    Because their testing was conducted before Windows 2000's generic availability ship date, they were not able to evaluate its hard-copy documentation. The online documentation provided on a CD is extensive, useful and well-organized, although a Web interface would subsist much easier to utilize if it gave more than a pair of sentences at a time for a particular assist topic.

    NetWare 5 comes with two manuals: a minute manual for installing and configuring the NOS with proper explanations of concepts and features along with an overview of how to configure them, and a little spiral-bound booklet of quick start cards. Novell's online documentation is very helpful.

    Red Hat Linux comes with three manuals - an installation guide, a getting started pilot and a reference manual - totality of which are facile to follow.

    Despite being the most difficult product to install, UnixWare offers the best documentation. It comes with two manuals: a system handbook and a getting started guide. The system handbook is a reference for conducting the installation of the operating system. It does a proper job of reflecting this painful experience. The getting started pilot is well-written and well-organized. It covers many of the tools needed to configure and maintain the operating system. SCO's online documentation looks nice and is facile to follow.

    The bottom line is that these NOSes tender a wide purview of characteristics and provide enterprise customers with a much deal of option regarding how each can subsist used in any given corporate network.

    If you want a good, generic purpose NOS that can deliver enterprise-class services with totality the bells and whistles imaginable, then Windows 2000 is the strongest contender. However, for high performance, enterprise file and print services, their tests flaunt that Novell leads the pack. If you're willing to pay a higher cost for scalability and reliability, SCO UnixWare would subsist a safe bet.

    But if you need an inexpensive alternative that will give you bare-bones network services with decent performance, Red Hat Linux can certainly fit the bill.

    The option is yours.

    Bass is the technical director and Robinson is a senior technical staff member at Centennial Networking Labs (CNL) at North Carolina status University in Raleigh. CNL focuses on performance, capacity and features of networking and server technologies and equipment. They can subsist reached at john_bass@ncsu.edu and james_robinson@ncsu.edu.

    How they did it

    We tested each NOS on Compaq ProLiant 1600 servers with dual 650MHz Pentium III CPUs, 512K-byte L2 cache and 640M bytes of RAM. The data partition consisted of 14 9.1G-byte drives loaded in a Compaq RAID Array 4214 drive array connected to an on-board Ultra2 SCSI controller. The NOSes were loaded on a 9.1G-byte drive connected to a second on-board Ultra2 SCSI controller. This configuration increased the available bandwidth of the drive subsystem and alleviated the bandwidth bottleneck to the drives.The client hardware consisted of four ProLiant 1600 machines with dual 600MHz Pentium III CPUs and 640M bytes of RAM.

    Two additional ProLiant 1600 machines had dual 400MHz Pentium II chips with 256M bytes of RAM. Each client system ran Windows NT Server 4.0.Servers and clients were connected to the network with Intel Pro 100+ network interface cards (NIC). A Cisco leavening 2900 switch with 24 10/100M bit/sec Ethernet ports completed the network configuration. totality the NICs and switch ports were configured for 100M bit/sec full-duplex operation. They used an additional Compaq 1600 with four Ethernet NICs as the control machine.For their NOS benchmarking, they focused on file service and network performance.

    To test file service performance, they used Client/Server Solution's Benchmark Factory tool, which let us create tests that would stress each operating system's file subsystem. They configured the server to provide a Windows network file partake for totality clients using Windows System Message block protocol over IP.

    We installed a benchmark agent on each client and modified the clients' LMHOSTS files to evenly divide file transaction requests to the server. They divided the tests into two categories - little and big file transfers.For the little file transfer tests, they used a 3-D test matrix of transfer direction (read/write), block size (1K and 8K bytes) and transaction sort (random/ sequential), which resulted in eight individual tests. The little file transfer tests used a mix of 80 percent 1K-byte files, 10 percent 10K-byte files and 10 percent 50K-byte files. totality of these write transaction tests were conducted with a write through flag set in the Benchmark Factory software. This flag is set to simulate an application forcing a write through each operating system's cache to disk.Because many applications attain not constrain a write to disk, they asked Benchmark Factory to recompile its code with the write through flag turned off, and they reran the test with the current benchmark software build.

    For the big file transfer tests, they combined reads and writes together in the selfsame tests to emulate the deportment of big file service operations. They used a mix of 90 percent reads and 10 percent writes. They then created a set of four tests to cover totality combinations of transfer sort (random/sequential) and block size (1K and 8K bytes). The big file transfer tests used a mix of 80 percent 500K-byte files and 20 percent 1M-byte files. totality of these write transaction tests were conducted with the write through flag set in the Benchmark Factory software. They reran the tests with the write through flag turned off.The benchmarking agent created the files each virtual user needed at the dawn of each test. They ran five iterations of each test with an increasing load of virtual users starting at one and increasing to 200 by 50-user increments for the majority of their tests. However, for their sequential read/write tests they started at one and increased to 40 in 10-user increments.

    We did introductory testing to establish the test parameters, then ran those parameters against each NOS.We graphed the results of each file test on a curve with five data points. The curves beget a knee followed by a plateau. They averaged the data points in the plateau to submit the score for the test. They normalized the raw scores for each of the 20 file tests and then factored those normalized scores together to obtain a file benchmark score.To test the network performance of each NOS, they used Ganymede Software's Chariot software, which differs from the Benchmark Factory software in that totality file transactions occur in memory. The disk subsystem is not utilized. They used Chariot to compare the efficiency of the NIC drivers and TCP/ IP stacks as measured by the number of operations each NOS could fulfill before the processor was bottlenecked and to compare the baseline throughput of the servers.For the TCP stack test, they only used two NICs on the server and disabled the other two. They set the IP subnet mask on totality the machines to 255.255.252.0, which allot 100.0.1.x and 100.0.2.x in the selfsame subnet.We set up several bidirectional streams of short TCP file transfers from each of the clients to the server. A TCP session was built and torn down for each 3K-byte file transferred. This allot a hefty load on the processors. Because the processors are the bottleneck, this test indicates the efficiency of the TCP stack and NIC driver for each NOS. They ran this test for 10 minutes and recorded the aggregate throughput value for totality the streams.We ran a second Ganymede test to come by an concept of the objective aggregate throughput of totality four NICs on the server.

    The bidirectional streams between the Chariot endpoints were configured as a long TCP session with a big file size of 10M bytes. The tests opened a TCP session once when they began and then sent files for the duration of the test.

    The session was not closed until the halt of the test. They ran this test for 10 minutes to come by an objective aggregate throughput measurement. They averaged the short and long TCP file transaction results to come by one number measured in megabits per second. This number was normalized to obtain the score for the network test.We likewise took a qualitative gape at each NOS's management tools, security measures, stability and fault-tolerance features, installation process and documentation.We evaluated the usability of the overall management interface and how each product handled server monitoring, client administration, and file, print and storage management. They evaluated the scalability of each NOS based on its symmetric multiprocessor ability, failover clustering champion and load-balancing clustering ability. For their security evaluation, they examined password file encryption, password and user ID encryption over the network, and any advanced security features offered. For stability and foible tolerance, they looked at each product's software RAID capabilities, backup and restore utilities, and memory protection.

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    More About Filesystems | killexams.com real questions and Pass4sure dumps

    This chapter is from the book 

    If they consider filesystems as a mechanism for both storing and locating data, then the two key elements for any filesystem are the items being stored and the list of where those items are. The deeper details of how a given filesystem manipulates its data and meta-information stagger beyond the scope of this chapter but are addressed further in Appendix B, "Anatomy of a Filesystem."

    Filesystem Components That the Admin Needs to Know About

    As always, they need to come by a handle on the vocabulary before they can understand how the elements of a filesystem work together. The next three sections portray the basic components with which you, as a sysadmin, need to subsist familiar.

    Files

    The most intuitively obvious components of a filesystem are, of course, its files. Because everything in UNIX is a file, special functions are differentiated by file type. There are fewer file types than you might imagine, as Table 3.2 shows.

    Table 3.2 File Types and Purposes, with Examples

    File Type

    Purpose/Contents

    Examples

    Directory

    Maintains information for directory structure

    /

    /usr

    /etc

    Block special

    Buffered device file

    Linux: /dev/hda1

    Solaris: /dev/dsk/c0t0d0s0

    Character special

    Raw device file

    Linux: /dev/tty0

    Solaris: /dev/rdsk/c0t0d0s0

    UNIX domain socket

    Interprocess communication (IPC)

    See output of commands for files Linux: netstat –x Solaris: netstat -f unix

    Named pipe special (FIFO device)

    First-in-first-out IPC mechanism, Invoked by name

    Linux: /dev/initctl Solaris: /etc/utmppipe/etc/cron.d/FIFO

    Symbolic link

    Pointer to another file (any type)

    /usr/tmp -> ../var/tmp

    Regular

    All other files; holds data of totality other types

    Text files remonstrate files Database files Executables/binaries

    Notice that directories are a sort of file. The key is that they beget a specific sort of format and contents (see Appendix B for more details). A directory holds the filenames and index numbers (see the following section, "Inodes") of totality its constituent files, including subdirectories.

    Directory files are not flat (or regular) files, but are indexed (like a database), so that you can still locate a file quickly when you beget a big number of files in the selfsame directory.13

    Even though file handling is generally transparent, it is captious to recall that a file's data blocks14 may not subsist stored sequentially (or even in the selfsame generic disk region). When data blocks are widely scattered in an uncoordinated manner, it can impress access times and multiply I/O overhead.

    Inodes

    Meta-information about files is stored in structures called index nodes, or inodes. Their contents vary based on the particular filesystem in use, but totality inodes hold the following information about the file they index:15

  • Inode identification number

  • File type

  • Owners: user and group

  • UNIX permissions

  • File size

  • Timestamps

  • ctime: ultimate file status change time

  • mtime: ultimate data modification time16

  • atime: ultimate access time

  • Reference/link count

  • Physical location information for data blocks

  • Notice that the filename is not stored in the inode, but as an entry in the file's closest parent directory.

    All other information about a file that ls displays is stored in an inode somewhere. With a few handy options, you can haul out lots of useful information. Let's whine that you want to know the inode number of the Solaris kernel.17 You just give the –i option, and voilá:

    [sun:10 ~]ls -i /kernel/genunix

    264206 genunix

    Of course, ls –l is an faded friend, telling you most everything that you want to know. Looking at the Solaris kernel again, you come by the output in device 3.4.

    Figure 3.4 Diagrammed Output of ls on a File

    Notice that the timestamp shown by default in a long listing is mtime. You can pass various options to ls to view ctime and atime instead. For other nifty permutations, note the ls man page.

    File Permissions and Ownership Refresher

    Because UNIX was designed to champion many users, the question naturally arises how to know who can note what files. The first and simplest respond is simply to permit users to examine only their own files. This, of course, would accomplish it difficult, if not impossible, to share, creating much difficulties in collaborative environments and causing a string of other problems: Why can't I elope ls? Because the system created it, not you, is only the most obvious example of such problems.

    Users and Groups

    UNIX uses a three-part system to determine file access: There's what you, as the file owner, are allowed to do; there's what the group is allowed to do; and there's what other people are allowed to do. Let's note what Elvis's permissions gape like:

    [ elvis@frogbog elvis ]$ ls -l

    total 36

    drwxr-xr-x 5 elvis users 4096 Dec 9 21:55 Desktop

    drwxr-xr-x 2 elvis users 4096 Dec 9 22:00 Mail

    -rw-r--r-- 1 elvis users 36 Dec 9 22:00 README

    -rw-r--r-- 1 elvis users 22 Dec 9 21:59 ThisFile

    drwxr-xr-x 2 elvis users 4096 Dec 12 19:57 arc

    drwxr-xr-x 2 elvis users 4096 Dec 10 00:40 songs

    -rw-r--r-- 1 elvis users 46 Dec 12 19:52 tao.txt

    -rw-r--r-- 1 elvis users 21 Dec 9 21:59 thisfile

    -rw-r--r-- 1 elvis users 45 Dec 12 19:52 west.txt

    As long as we're here, let's demolish down exactly what's being displayed. First, they beget a 10-character string of letters and hyphens. This is the representation of permissions, which I'll demolish down in a minute. The second particular is a number, usually a solitary digit. This is the number of hard links to that directory. I'll discuss this later in this chapter. The third thing is the username of the file owner, and the fourth is the title of the file's group. The fifth column is a number representing the size of the file, in bytes. The sixth contains the date and time of ultimate modification for the file, and the final column shows the filename.

    Every user on the system has a username and a number that is associated with that user. This number generally is referred to as the UID, short for user ID. If a user has been deleted but, for some reason, his files remain, the username is replaced with that user's UID. Similarly, if a group is deleted but still owns files, the GID (group number) shows up instead of a title in the group field. There are likewise other circumstances in which the system can't correlate the title and the number, but these should subsist relatively rare occurrences.

    As a user, you can't change the owner of your files: This would open up some sedate security holes on the system. Only root can chown files, but if he makes a mistake, you can now put a question to root to chown the files to you. As a user, you can chgrp a file to a different group of which you are a member. That is, if Elvis is a member of a group named users and a group named elvis, he can chgrp elvis west.txt or chgrp users west.txt, but because he's not a member of the group beatles, he can't chgrp beatles west.txt. A user can belong to any number of groups. Generally (although this varies not much by flavor), files created belong to the group to which the directory belongs. On most modern UNIX variants, the group that owns files is whatever group is listed as your primary group by the system in the /etc/passwd file and can subsist changed via the newgrp command. On these systems, Elvis can chgrp users if he wants his files to belong to the users group, or he can chgrp elvis if he wants his files to belong to the elvis group.

    Reading Permissions

    So, what were those humorous strings of letters and hyphens at the dawn of each long directory listing? I already said that they represented the permissions of the file, but that's not especially helpful. The 10 characters of that string picture the consent bits for each file. The first character is separate, and the ultimate nine are three very similar groups of three characters. I'll interpret each of these in turn.

    If you gape back to Elvis's long listing of his directory, you'll note that most of the files simply beget a hyphen as the first character, whereas several possess a d in this field. The more astute reader might note that the files with a d in that first territory totality befall to subsist directories. There's a proper reason for this: The first permissions character denotes whether that file is a special file of one sort or another.

    What's a special file? It's either something that isn't really a file (in the sense of a sequential stream of bytes on a disk) but that UNIX treats as a file, such as a disk or a video display, or something that is really a file but that is treated differently. A directory, by necessity, is a stream of bytes on disk, but that d means that it's treated differently.

    The next three characters picture what the user who owns the file can attain with it. From left to right, these permissions are read, write, and execute. Read consent is just that—the capability to note the contents of a file. Write consent implies not only the right to change the contents of a file, but likewise the right to delete it. If I attain not possess write consent to a file, rm not_ permitted.txt fails.

    Execute consent determines whether the file is likewise a command that can subsist elope on the system. Because UNIX sees everything as a file, totality commands are stored in files that can subsist created, modified, and deleted fancy any other file. The computer then needs a course to narrate what can and can't subsist run. The execute bit does this.

    Another captious reason that you need to worry about whether a file is executable is that some programs are designed to subsist elope only by the system administrator: These programs can modify the computer's configuration or can subsist Dangerous in some other way. Because UNIX enables you to specify permissions for the owner, the group, and other users, the execute bit enables the administrator to restrict the utilize of Dangerous programs.

    Directories deal the execute consent differently. If a directory does not beget execute permissions, that user (or group, or other users on the system) can't cd into that directory and can't gape at information about the files in that directory. (You usually can find the names of the files, however.) Even if you beget permissions for the files in that directory, you generally can't gape at them. (This varies not much by platform.)

    The second set of three characters is the group permissions (read, write, and execute, in that order), and the final set of three characters is what other users on the system are permitted to attain with that file. Because of security concerns (either due to other users on your system or due to pervasive networks such as the Internet), giving write access to other users is highly discouraged.

    Changing Permissions

    Great, you can now read the permissions in the directory listing, but what can you attain with them? Let's whine that Elvis wants to accomplish his directory readable only by himself. He can chmod go-rwx ~/songs: That means remove the read, write, and execute permissions for the group and others on the system. If Elvis decides to let Nashville artists consume a gape at his material but not change it (and if there's a group nashville on the system), he can first chgrp nashville songs and then chmod g+r songs.

    If Elvis does this, however, he'll find that (at least, on some platforms) members of group nashville can't gape at them. Oops! With a simple chmod g+x songs, the problem is solved:

    [ elvis@frogbog elvis ]$ ls -l

    total 36

    drwxr-xr-x 5 elvis users 4096 Dec 9 21:55 Desktop

    drwxr-xr-x 2 elvis users 4096 Dec 9 22:00 Mail

    -rw-r--r-- 1 elvis users 36 Dec 9 22:00 README

    -rw-r--r-- 1 elvis users 22 Dec 9 21:59 ThisFile

    drwxr-xr-x 2 elvis users 4096 Dec 12 19:57 arc

    drwxr-x--- 2 elvis nashvill 4096 Dec 15 14:21 songs

    -rw-r--r-- 1 elvis users 46 Dec 12 19:52 tao.txt

    -rw-r--r-- 1 elvis users 21 Dec 9 21:59 thisfile

    -rw-r--r-- 1 elvis users 45 Dec 12 19:52 west.txt

    Special Permissions

    In addition to the read, write, and execute bits, there exists special permissions used by the system to determine how and when to suspend the prevalent consent rules. Any thorough understanding of UNIX requires an understanding of the setuid, setgid, and sticky bits. For prevalent system users, only a generic understanding of these is necessary, and this discussion is thus brief. proper documentation on this matter exists elsewhere for budding system administrators and programmers.

    setuid

    The setuid bit applies only to executable files and directories. In the case of executable programs, it means that the given program runs as though the file owner were running it. That is, xhextris, a variant on Tetris, has the following permissions on my system:

    -rwsr-xr-x

    1 games games 32516 May 18 1999 /usr/X11R6/bin/xhextris

    There's a pseudouser called games on the system, which can't subsist logged into and has no home directory. When the xhextris program executes, it can read and write to files that only the game's pseudouser normally would subsist permitted. In this case, there's a high-score file stored on the system that writeable only by that user. When Elvis runs the game, the system acts as though he were the user games, and thus he is able to store the high-score file. To set the setuid bit on a file, you can narrate chmod to give it mode u+s. (You can deem of this as uid set, although this isn't technically accurate.)

    setgid

    The setgid bit, which stands for "set group id," works almost identically to setuid, except that the system acts as though the user's group is that of the given file. If xhextris had used setgid games instead of setuid games, the high score would subsist writeable to any directory owned by the group games. It is used by the system administrator in ways fundamentally similar to the setuid permission.

    When applied to directories on Linux, Irix, and Solaris (and probably most other POSIX-compliant UNIX flavors as well), the setgid bit means that current files are given the parent directory's group rather than the user's primary or current group. This can subsist useful for, say, a directory for fonts built by (and for) a given program. Any user might generate the fonts via a setgid command that writes to a setgid directory. setgid on directories varies by platform; check your documentation. To set the setgid bit, you can narrate chmod to utilize g+s (gid set).

    sticky

    Although a file in a group or world-writeable directory without the sticky bit can subsist deleted by anyone with write consent for that directory (user, group, or other), a file in a directory with the sticky bit set can subsist deleted only by either the file's owner or root. This is particularly useful for creating temporary directories or scratch space that can subsist used by anyone without one's files being deleted by others. You can set consent +t in chmod to give something the sticky bit.

    Numeric Permissions

    Like almost everything else on UNIX, permissions beget a number associated with them. It's generally considered that permissions are a group of four digits, each between 0 and 7. Each of those digits represents a group of three permissions, each of which is a yes/no answer. From left to right, those digits picture special permissions, user permissions, group permissions, and other permissions.

    So, About Those consent Bits...

    Most programs reading consent bits expect four digits, although often only three are given. Shorter numbers are filled in with leading zeros: 222 is treated as 0222, and 5 is treated as 0005. The three rightmost digits are, as previously mentioned, user (owner) permissions, group permissions, and other permissions, from right to left.

    Each of these digits is calculated in the following manner: read consent has a value of 4, write consent has a value of 2, and execute consent has a value of 1. Simply add these values together, and you've got that consent value. Read, write, and execute would subsist 7, read and write without execute would subsist 6, and no consent to attain anything would subsist 0. Read, write, and execute for the file owner, with read and execute for the group and nothing at totality for anyone else, would subsist 750. Read and write for the user and group, but only read for others, would subsist 664.

    The special permissions are 4 for setuid, 2 for setgid, and 1 for sticky. This digit is prepended to the three-digit numeric permission: A temporary directory with sticky read, write, and execute consent for everyone would subsist mode 1777. A setuid root directory writeable by nobody else would subsist 4700. You can utilize chmod to set numeric permissions directly, as in chmod 1777 /tmp.

    umask

    In addition to a more precise utilize of chmod, numeric permissions are used with the umask command, which sets the default permissions. More precisely, it "masks" the default permissions: The umask value is subtracted from the maximum practicable settings.* umask deals only with the three-digit permission, not the full-fledged four-digit value. A umask of 002 or 022 is most commonly the default. 022, subtracted from 777, is 755: read, write, and execute for the user, and read and execute for the group and others. 002 from 777 is 775: read, write, and execute for the user and group, and read and execute for others. I mind to set my umask to 077: read, write, and execute for myself, and nothing for my group or others. (Of course, when working on a group project, I set my umask to 007: My group and I can read, write, or execute anything, but others can't attain anything with their files.)

    You should note that the umask assumes that the execute bit on the file will subsist set. totality umasks are subtracted from 777 rather than 666, and those extra ones are subtracted later, if necessary. (See Appendix B for more details on consent bits and umask workings.)

    *Actually, the consent bits are XORed with the maximum practicable settings, if you're a computer science type.

    Also notice that the first bit of output prepended to the permissions string indicates the file type. This is one handy course of identifying a file's type. Another is the file command, as shown in Table 3.3.

    Table 3.3 ls File Types and file Output Sample

    File Type

    ls File sort Character

    File array Example

    Directory

    d

    [either:1 ~]file /usr/usr: directory

    Block special device

    b

    [linux: 10 ~] file /dev/hda1/dev/hda1: block special (3/1)[sun:10 root ~]file /dev/dsk/c0t0d0s0/dev/dsk/c0t0d0s0: block special(136/0)

    Character special device

    c

    [linux:11 ~] file /dev/tty0/dev/tty0: character special (4/0)

    [ensis:11 ~]file /dev/rdsk/c0t0d0s0/dev/rdsk/c0t0d0s0: character special (136/0)

    UNIX domain socket

    s

    [linux:12 ~] file /dev/log/dev/log: socket

    [sun:12 ~]file /dev/ccv/dev/ccv: socket

    Named pipe special (FIFO device)

    p

    [linux:13 ~] file /dev/initctl/dev/initctl: fifo (named pipe)

    [sun:13 ~]file /etc/utmppipe/etc/utmppipe: fifo

    Symbolic link

    l

    [linux:14 ~] file /usr/tmp/usr/tmp: symbolic link to ../var/tmp

    [sun:14 ~]file -h /usr/tmp/usr/tmp: symbolic link to ¬../var/tmp

    Regular

    -

    [linux:15 ~] file /etc/passwd/etc/passwd: ASCII text

    [linux:15 ~] file /boot/vmlinux-2.4.2-2/boot/vmlinux-2.4.2-2: ELF 32-bit LSB executable,

    ¬Intel 80386, version 1,statically linked, not stripped

    [linux:15 ~] file /etc/rc.d/init.d/sshd/etc/rc.d/init.d/sshd: Bourne-Again shell script text executable

    [sun:15 ~]file /etc/passwd

    /etc/passwd: ascii text

    [sun:15 ~]file /kernel/genunix

    -/kernel/genunix: ELF 32-bit MSB relocatable

    ¬SPARC Version 1

    [sun:15 ~]file /etc/init.d/sshd

    /etc/init.d/sshd: executable

    ¬/sbin/sh script

    Notice the in-depth information that file gives—in many cases, it shows details about the file that no other command will readily array (such as what kindhearted of executable the file is). These low-level details are beyond the scope of their discussion, but the man page has more information.

    Important Points about the file ommand

    file tries to device out what sort a file is based on three types of test:

  • The file sort that the ls –l command returns.

  • -The presence of a magic number at the dawn of the file identifying the file type. These numbers are defined in the file /usr/share/magic in Red Hat Linux 7.1 and /usr/lib/locale/locale/LC_MESSAGES/magic (or /etc/magic) in Solaris 8. Typically, only binary files will beget magic numbers.

  • -In the case of a regular/text file, the first few bytes are tested to determine the sort of text representation and then to determine whether the file has a recognized purpose, such as C code or a Perl script.

  • file actually opens the file and changes the atime in the inode.

    Inode lists are maintained by the filesystem itself, including which ones are free for use. Inode allocation and manipulation is totality transparent to both sysadmins and users.

    Inodes become significant at two times for the sysadmin: at filesystem creation time and when the filesystem runs out of free inodes. At filesystem creation time, the total number of inodes for the filesystem is allocated. Although they are not in use, space is set aside for them. You cannot add any more inodes to a filesystem after it has been created. When you elope out of inodes, you must either free some up (by deleting or moving files) or migrate to another, larger filesystem.

    Without inodes, files are just a random assortment of ones and zeros on the disk. There is no guarantee that the file will subsist stored sequentially within a sector or track, so without an inode to point the course to the data blocks, the file is lost. In fact, every file is uniquely identified by the combination of its filesystem title and inode number.

    See Appendix B for more minute information on the exact content of inodes and their structure.

    Linux has a very useful command called stat that dumps the contents of an inode in a tidy format:

    [linux:9 ~]stat . File: "." Size: 16384 Filetype: Directory Mode: (0755/drwxr-xr-x) Uid: (19529/ robin) Gid:(20/users) Device: 0,4 Inode: 153288707 Links: 78 Access: Sun Jul 22 13:58:29 2001(00009.04:37:59) Modify: Sun Jul 22 13:58:29 2001(00009.04:37:59) Change: Sun Jul 22 13:58:29 2001(00009.04:37:59) Boot block and Superblock

    When a filesystem is created, two structures are automatically created, whether they are immediately used or not. The first is called the boot block, where boot-time information is stored. Because a partition may subsist made bootable at will, this structure needs to subsist available at totality times.

    The other structure, of more interest here, is the superblock. Just as an inode contains meta-information about a file, a superblock contains metainformation about a filesystem. Some of the more captious contents are listed here:18

  • Filesystem name

  • Filesystem size

  • Timestamp: ultimate update

  • Superblock status flag

  • Filesystem status flag: clean, stable, active

  • Number of free blocks

  • List of free blocks

  • Pointer to next free block

  • Size of inode list

  • Number of free inodes

  • List of free inodes

  • Pointer to next free inode

  • Lock fields for free blocks and inodes

  • Summary data block

  • And you thought inodes were complex.

    The superblock keeps track of free file blocks and free inodes so that the filesystem can store current files. Without these lists and pointers, a long, sequential search would beget to subsist performed to find free space every time a file was created.

    In much the selfsame course that files without inodes are lost, filesystems without intact superblocks are inaccessible. That's why there is a superblock status flag—to indicate whether the superblock was properly and completely updated before the disk (or system) was ultimate taken offline. If it was not, then a consistency check must subsist performed for the gross filesystem and the results stored back in the superblock.

    Again, more minute information about the superblock and its role in UNIX filesystems may subsist institute in Appendix B.

    Filesystem Types

    Both Red Hat and Solaris recognize a host of different filesystem types, although you will generally halt up using and supporting just a few. There are three touchstone types of filesystem—local, network, and pseudo—and a fourth "super-filesystem" sort that is actually losing ground, given the size of modern disks.

    Local Filesystems

    Local filesystems are common to every system that has its own local disk.19 Although there are many instances of this sort of filesystem, they are totality designed to work within a system, managing the components discussed in the ultimate section and interfacing with the physical drive(s).

    Only a few local filesystems are specifically designed to subsist cross-platform (and sometimes even cross–OS-type). They achieve in handy, though, when you beget a nondisk hardware failure; you can just consume the disk and allot it into another machine to retrieve the data.20 The UNIX File System, or ufs, was designed for this; both Solaris and Red Hat Linux machines can utilize disks with this filesystem. Note that Solaris uses ufs filesystems by default. Red Hat's default local filesystem is ext2.

    Another local, cross-platform filesystem is ISO9660, the CD-ROM standard. This is why you can read your Solaris CD in a Red Hat box's reader.

    Local filesystems achieve in two related but sever flavors. The original, touchstone model filesystem is still in broad utilize today. The newer journaling filesystem sort is just dawn to really achieve into its own. The major contrast between the two types is the course they track changes and attain integrity checks.

    Standard Filesystems

    Standard, nonjournaling filesystems rely on flags in the superblock for consistency regulation. If the superblock flag is not set to "clean," then the filesystem knows that it was not shut down properly: not totality write buffers were flushed to disk, and so on. Inconsistency in a filesystem means that allocated inodes could subsist overwritten; free inodes could subsist counted as in use—in short, rampant file corruption, mass hysteria.

    But there is a filesystem integrity checker to rescue the day: fsck. This command is usually invoked automatically at boot-time to verify that totality filesystems are clean and stable. If the / or /usr filesystems are inconsistent, the system might prompt you to start up a miniroot shell and manually elope fsck. A few of the more captious items checked and corrected are listed here:

  • Unclaimed blocks and inodes (not in free list or in use)

  • Unreferenced but allocated blocks and inodes

  • Multiply claimed blocks and inodes

  • Bad inode formats

  • Bad directory formats

  • Bad free block or inode list formats

  • Incorrect free block or inode counts

  • Superblock counts and flags

  • Note that a filesystem should subsist unmounted before running fsck (see the later section "Administering Local Filesystems"). Running fsck on a mounted filesystem might antecedent a system panic and crash, or it might simply spurn to elope at all. It's likewise best, though not required, that you elope fsck on the raw device, when possible. note the man page for more details and options.

    So where does fsck allot orphans, the blocks and inodes that are clearly in utilize but aren't referenced anywhere? Enter the lost+found directories. There is always a /lost+found directory on every system; other directories accrue them as fsck finds orphans in their purview. fsck automatically creates the directories as needed and renames the lost blocks into there by inode number. note the man pages "mklost+found" on Red Hat and "fsck_ufs" on Solaris.

    Journaling Filesystems

    Journaling filesystems attain away with fsck and its concomitant superblock structures. totality filesystem status information is internally tracked and monitored, in much the selfsame course that databases systems set up checkpoints and self-verifications.

    With journaling filesystems, you beget a better casual of complete data recovery in the event of a system crash. Even unsaved data in buffers can subsist recovered thanks to the internal log.21 This kindhearted of foible tolerance makes journaling filesystems useful in high- availability environments.

    The drawback, of course, is that when a filesystem fancy this gets corrupted somehow, it presents major difficulties for recovery. Most journaling filesystems provide their own salvaging programs for utilize in case of emergency. This underscores how captious backups are, no matter what kindhearted of filesystem software you've invested in. note Chapter 16, "Backups," for more information.

    One of the earliest journaling filesystems is still a commercial venture: VxFS by Veritas. Another pioneer has decided to release its software into the public domain under GPL22 licensing: JFS23 by IBM. SGI's xfs journaling filesystem has been freely available under GPL since about 1999, although it is only designed to work under IRIX and Linux.24

    Maintenance of filesystem status incurs an overhead when using journaling filesystems. As a result, these filesystems fulfill suboptimally for little filesystem sizes. Generally, journaling filesystems are arrogate for filesystem sizes of 500Mb or more.

    Network Filesystems

    Network-based filesystems are really add-ons to local filesystems because the file server must beget the actual data stored in one of its own local filesystems.25 Network file- systems beget both a server and client program.

    The server usually runs as a daemon on the system that is sharing disk space. The server's local filesystems are unaffected by this extra process. In fact, the daemon generally only puts a few messages in the syslog and is otherwise only visible through ps.

    The system that wants to access the server's disk space runs the client program to mount the shared filesystems across the network. The client program handles totality the I/O so that the network filesystem behaves just a fancy a local filesystem toward the client machine.

    The faded standby for network-based filesystems is the Network File System (NFS). The NFS touchstone is currently up to revision 3, though there are quite a number of implementations with their own version numbers. Both Red Hat and Solaris achieve touchstone with NFS client and server packages. For more details on the inner workings and configuration of NFS, note Chapter 13, "File Sharing."

    Other network-based filesystems comprise AFS (IBM's Andrew File System) and DFS/DCE (Distributed File System, allotment of the Open Group's Distributed Computing Environment). The mechanisms of these advanced filesystems stagger beyond the scope of this book, although their goal is still the same: to efficiently partake files across the network transparently to the user.

    Pseudo Filesystems

    Pseudofilesystems are an involving evolution in that they are not actually related to disk-based partitions. They are instead purely ratiocinative constructs that picture information and meta-information in a hierarchical structure. Because of this structure and because they can subsist manipulated with the mount command, they are still referred to as filesystems.

    The best example of pseudofilesystems exists on both Red Hat and Solaris systems: /proc. Under Solaris, /proc is restricted to just managing process information:

    [sun:1 ~]ls /proc 0 145 162 195 206 230 262 265 272 286 299 303 342 370 403 408 _672 752 1 155 185 198 214 243 263 266 278 292 3 318 360 371 404 52 _674 142 157 192 2 224 252 264 268 280 298 302 319 364 400 406 58 _678

    Note that these directories are totality named according to the process numbers corresponding to what you would find in the output of ps. The contents of each directory are the various meta-information that the system needs to manage the process.

    Under Red Hat, /proc provides information about processes as well as about various system components and statistics:

    [linux:1 ~] ls /proc 1 18767 23156 24484 25567 28163 4 493 674 8453 ksyms _stat 13557 18933 23157 24486 25600 3 405 5 675 9833 loadavg _swaps 13560 18934 23158 24487 25602 3050 418 5037 676 9834 locks _sys 13561 18937 23180 24512 25603 3051 427 5038 7386 9835 mdstat _tty 1647 19709 23902 24541 25771 3052 441 5054 7387 bus meminfo _uptime 1648 19730 23903 24775 25772 30709 455 5082 7388 cmdline misc _version 1649 19732 23936 25494 25773 30710 473 510 7414 cpuinfo modules 16553 19733 24118 25503 25824 30712 485 5101 7636 devices mounts 18658 2 24119 25504 25882 30729 486 524 7637 dma mtrr 18660 21450 24120 25527 25920 320 487 558 7638 filesystems net 18661 21462 24144 25533 26070 335 488 6 7662 fs _partitions 18684 21866 24274 25534 26071 337 489 670 8426 interrupts pci 18685 21869 24276 25541 26072 338 490 671 8427 ioports scsi 18686 21870 24277 25542 28161 339 491 672 8428 kcore self 18691 21954 24458 25543 28162 365 492 673 8429 kmsg slabinfo

    Again they note the directories named for process numbers, but they likewise note directories with indicative names such as cpuinfo and loadavg. Because this is a hierarchical filesystem, you can cd into these directories and read the various files for their system information.

    The most involving thing about /proc is that it allows even processes to subsist treated fancy files.26 This means that pretty much everything in UNIX, whether it is something that just exists or something that actually happens, can now subsist considered a file.

    For more information under Red Hat, sort man proc. For more information under Solaris, sort man –s 4 proc.

    Logical Volumes

    Finally, there are the "super-filesystems" or ratiocinative volumes that attain what the other major types of filesystem cannot: surmount the barriers of partitions. You may well put a question to why anyone would want to attain that. There are two reasons. First, because disks used to subsist a lot smaller and more costly, you used what you had at hand. If you needed a big pool of disk space, ratiocinative volumes allowed you to aggregate remnants into something useable. Second, even with larger disks, you still might not subsist able to achieve the kindhearted of disk space required by a particular researcher or program. Once again, ratiocinative volumes allow you to aggregate partitions across disks to profile one big filesystem.

    Crossing disk boundaries with a ratiocinative volume is referred to as disk spanning. Once you beget ratiocinative volumes, you can likewise beget some fairly complicated data management methods and performance-enhancing techniques. Disk striping, for example, is a performance booster. Instead of sequentially filling one disk and then the next in series, it spreads the data in discrete chunks across disks, allowing better I/O response through parallel operations.

    RAID27 implements ratiocinative volumes at 10 sever levels, with various features at each level. This implementation can subsist done either in hardware or in software, although the nomenclature for both is the same.28

    Table 3.4 RAID Levels

    RAID Level

    Features

    Implications

    0

    Disk striping

    Fastest

    Not self-repairing

    1

    Disk mirroring

    Fast

    Self-repairing

    -Requires extra drives for data duplication

    2

    Disk striping

    Fast

    Error correction

    Self-repairing

    (Very similar to RAID-3)

    3

    Disk striping

    Slower

    Parity disk

    Self-repairing

    Error correction

    Requires sever parity disk

    4

    Disk striping

    Slower

    Parity disk

    Self-repairing

    Requires sever parity disk

    (Very similar to RAID-5)

    5

    Disk striping

    Slowest for writes, but

    Rotating parity array

    good for reads

    Self-repairing

    Requires three to five sever parity disks

    Reconstruction by parity data (not duplication)

    6

    RAID-5 + secondary

    Not in broad use

    parity scheme

    7

    RAID-5 + real-time embedded controller

    Not in broad use

    0+1

    Mirrored striping

    -RAID-0 array duplicated (mirrored)

    1+0

    Striped mirroring

    -Each stripe is RAID-1 (mirrored) array

    High cost

    0+3

    Array of parity stripes

    Each stripe is RAID-3 array

    High cost

    Clearly, the kindhearted of complexity inherent in totality ratiocinative volume systems requires some kindhearted of back-end management system. Red Hat offers the ratiocinative Volume Manager (LVM) as a kernel module. While the details of LVM are beyond the scope of this book, it is involving to note that you can allot any filesystem that you want on top of the ratiocinative volume. Start at http://www.linuxdoc.org/HOWTO/LVM-HOWTO.htmlfor more details.

    Although Sun offers ratiocinative volume management, it is through a for-pay program called "Solstice DiskSuite." The filesystem on DiskSuite ratiocinative volumes must subsist ufs. For more information, start at http://docs.sun.com/ab2/coll.260.2/DISKSUITEREF.

    Another commercial ratiocinative volume manager for Solaris comes from Veritas; see: http://www.veritas.com/us/products/volumemanager/faq.html#a24

    The beauty of totality ratiocinative volumes is that they issue to subsist just another local filesystem and are completely transparent to the user. However, ratiocinative volumes attain add some complexity for the systems administrator, and the schema should subsist carefully documented on paper, in case it needs to subsist re-created.

    NAS

    Normally, a file server's disks are directly attached to the file server. With network-attached storage (NAS), the file server and the disks that it serves are sever entities, communicating over the local network. The storage disks require an aggregate controller that arbitrates file I/O requests from the external server(s). The server(s) and the aggregate controller each beget sever network IP addresses. To serve the files to clients, a file (or application) server sends file I/O requests to the NAS aggregate controller and relays the results back to client systems.

    NAS is touched on here for completeness—entire books can subsist written about NAS design and implementation. NAS does not really picture a sort of filesystem, but rather it is a mechanism to palliate the file server from the details of hardware disk access by isolating them in the network-attached storage unit.

    Red Hat Filesystem Reference Table

    Table 3.5 lists major filesystems that currently champion (or are supported by) Red Hat.29 The filesystem types that are currently natively supported are listed in /usr/src/linux/ fs/filesytems.c.

    Table 3.5 Filesystem Types and Purposes, with Examples (Red Hat)

    Filesystem Type

    Specific Instances (as Used in /etc/fstab)

    Purpose

    Local

    ext2

    Red Hat default filesystem

    ufs

    Solaris compatibility

    jfs

    Journaling filesystem from IBM

    xfs

    Journaling filesystem from SGI

    msdos

    Windows compatibility: DOS

    ntfs

    Windows compatibility: NT

    vfat

    Windows compatibility: FAT-32

    sysv

    SYS-V compatibility

    iso9660

    CD-ROM

    Adfs hfs romfs

    Others

    Affs hpfs smbfs

    Coda mnix udf

    devpts ncpfs umsdos

    efs qux4

    coherent

    Deprecated, pre-kernel 2.1.21

    ext

    xenix

    xiafs

    Network

    afs

    Network-based remote communication

    autofs

    nfs

    Pseudo

    proc

    Store process (and other system) meta-information

    Solaris Filesystem Reference Table

    Table 3.6 lists major filesystems that currently champion (or are supported by) Solaris. The filesystem types that currently are natively supported are listed as directories under /usr/lib/fs.

    Table 3.6 Filesystem Types and Purposes, with Examples (Solaris)

    Filesystem Type

    Specific Instances (as Used in /etc/vfstab)

    Purpose

    Local

    ufs

    Solaris default filesystem; Red Hat-compatible

    pcfs

    PC filesystem

    hsfs

    CD-ROM

    jfs

    Journaling filesystem from IBM

    Network

    afs

    Network-based remote communication

    nfs

    Pseudo

    procfs

    Store process metainformation

    Fdfs swapfs tmpfs

    Mount metainformation areas as filesystems

    mntfs cachefs lofs

    fifofs specfs udfs namefs



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