CentOS (Community ENTerprise Operating System) - the free operational system of a corporate level collected from initial texts Red Hat Enterprise Linux. Actually CentOS gives free RHEL for those to whom technical support from Red Hat is not necessary. First version CentOS 3, build4-rc0 has burn in the end 2003.

Project CentOS does not impose patches on SRPM-packages from Red Hat (short of trade marks change), therefore the system on 100% is compatible with RHEL and contains only free packages. Updatings can be received through yum - Yellow Dog Updater Modified (for the x86-version the apt-repository works).

CentOS has fast-growing community of admirers. Carefully fulfilled process of fast assembly, testing and release of corrections (errata), support through forums, IRC, dynamic section FAQ, and also an opportunity to get commercial support. CentOS 4.4 - the newest version of the distribution kit which are based on Red Hat Enterprise Linux 4 Update 4.

The kernel for CentOS is based on kernel Linux 2.4.21. Besides it includes the numerous additional opportunities taken from new experimental versions of a kernel. Among them Native Posix Threading Library (NPTL) and some the additional properties raising productivity of system.

In CentOS 4.4 support of greater server systems is improved. For x86 SMP-systems it is supported up to 16 logic CPU (8 pairs Hyperthreaded CPU) and up to 64GB the basic memory. The number of the devices supported by subsystems of input-output SCSI and Fiber Channel, is double (up to 256 devices). Also support of new storage systems, such as Serial ATA (SATA) is provided.

The new version includes the big set of protection means, such as support of lists ACL (Access Control List) for file systems ext2/3 which provide carrying out of more thin adjustments of the control of access to any object of file system. This opportunity is supported also on file systems NFS. Besides the new version includes support IPsec at a level of a kernel (the opportunity of cryptography at a level of a kernel is used).

• Rocks v4.1 (Fuji) the distribution kit for clusters, based on CentOS 4.2;
• SME Server;
• Asterisk@Home;
• Openfiler;
• Boston University’s Linux 4.5 Server Edition (Zodiac);
• NuOnce Networks CentOS ™ / Blue Quartz ™ CD.

• Oracle (9i, 9iRAC, 9i Application Server, 8i, 11i eBusiness Suite, Oracle collaboration Suite);
• VERITAS (Foundation Suite, VCS, NetBackup Business Server and Datacenter);
• BEA (WebLogic Server 7.0, WebLogic Jrockit);
• IBM (WebSphere v5, DB2 v8.1, various products Tivoli Products, Directory Server 5.1);
• Reuters (Reuters Market Data System);
• Plus key products from BMC, CA, EMC, Legato, Rogue Wave and many other things.

The given brief list of the basic properties of system represents only the general review of the serious improvements made in system CentOS. As system CentOS 4.4 puts the primary goal improvement of productivity, scalability, fault tolerance, development of applications and supports of standards, it by the right is the world leader among computing systems of an industrial level.

CentOS allows to create a cluster high reliability consisting of 2-8 computers. The technology "High availability clustering" (or "Failover clustering") is widely applied in commercial operational systems; at its use critical applications remain constantly accessible, their restoration after failures of the equipment or switching-off occurs automatically.

CentOS it is intended for people to whom stability of operating system of an industrial class is necessary, but expensive certification and technical support is not necessary. An official site of operational system CentOS - http://www.centos.org/