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XFS is a high-performance 64-bit journaling file system created by Silicon Graphics, Inc (SGI) in 1993.〔("''xFS: the extension of EFS - "x" for to-be-determined (but the name stuck)''" ), xfs.org〕 It was the default file system in the SGI's IRIX operating system starting with its version 5.3; the file system was ported to the Linux kernel in 2001. , XFS is supported by most Linux distributions, some of which use it as the default file system. XFS excels in the execution of parallel input/output (I/O) operations due to its design, which is based on allocation groups (a type of subdivision of the physical volumes in which XFS is used- also shortened to ''AGs''). Because of this, XFS enables extreme scalability of I/O threads, file system bandwidth, and size of files and of the file system itself when spanning multiple physical storage devices. XFS ensures the consistency of data by employing metadata journaling and supporting write barriers. Space allocation is performed via extents with data structures stored in B+ trees, improving the overall performance of the file system, especially when handling large files. Delayed allocation assists in the prevention of file system fragmentation; online defragmentation is also supported. A feature unique to XFS is the pre-allocation of I/O bandwidth at a pre-determined rate, which is suitable for many real-time applications; however, this feature was supported only on IRIX, and only with specialized hardware. A notable XFS user, NASA Advanced Supercomputing Division, takes advantage of these capabilities deploying two 300+ terabyte XFS filesystems on two SGI Altix archival storage servers, each of which is directly attached to multiple Fibre Channel disk arrays. ==History== Silicon Graphics began development of XFS in 1993, including it into IRIX for the first time in its version 5.3 in 1994. The file system was released under the GNU General Public License (GPL) in May 2000 and was ported to Linux by a team led by Steve Lord at SGI, while first support by a Linux distribution came in 2001. This support gradually became available in almost all Linux distributions. Linux kernel's support for XFS was originally available through patches from SGI. It was merged into the Linux kernel mainline for the 2.6 series, and separately merged in February 2004 into the 2.4 series in version 2.4.25, making XFS almost universally available on Linux systems.〔 〕 Gentoo Linux was the first Linux distribution to introduce an option for XFS to be used as the default filesystem in mid-2002.〔 〕 Installation programs for the Arch, Debian, Fedora, openSUSE, Kate OS, Mandriva, Slackware, Ubuntu, VectorLinux and Zenwalk Linux distributions all offer XFS as a choice of filesystem, but few of these let the user create XFS for the /boot filesystems due to deficiencies and unpredictable behavior in GRUB, generally the default bootloader.〔 〕 FreeBSD added read-only support for XFS in December 2005 and in June 2006 introduced experimental write support; however this was supposed to be used only as an aid in migration from Linux, not as a "main" file system. Support for XFS was removed in FreeBSD 10. In 2009, version 5.4 of 64-bit Red Hat Enterprise Linux (RHEL) Linux distribution contained the necessary kernel support for the creation and usage of XFS file systems, but did not contain the corresponding command-line tools. The tools available from CentOS could be used for that purpose, and they were previously also provided to RHEL customers on request.〔 〕 RHEL 6.0, released in 2010, includes XFS support for a fee as part of Red Hat's "scalable file system add-on".〔(【引用サイトリンク】url=http://ca.redhat.com/products/enterprise-linux-add-ons/file-systems/ )〕 Oracle Linux 6, which was released in 2011, also includes an option for using XFS. RHEL 7.0, released in June 2014, uses XFS as the default file system, including support for using XFS for the /boot partition. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「XFS」の詳細全文を読む スポンサード リンク
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