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| = '''<font face="ARIAL NARROW,HELVETICA"> XFS: A high-performance journaling filesystem </font>''' = | | == XFS Status Update Test Page == |
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| XFS combines advanced journaling technology with full 64-bit addressing and scalable structures and algorithms. This combination delivers the most scalable high-performance filesystem ever conceived.
| | * [[XFS status update for 2012]] ([[XFS_status_update_for_2012#XFS status update for February 2012|Latest]]) |
| | | * [[XFS status update for 2011]] ([[XFS_status_update_for_2011#XFS status update for December 2011|Latest]]) |
| == <font face="ARIAL NARROW,HELVETICA"> Questions and Problems </font> ==
| | * [[XFS status update for 2010]] ([[XFS_status_update_for_2010#XFS status update for December 2010|Latest]]) |
| | | * [[XFS status update for 2009]] ([[XFS_status_update_for_2009#XFS status update for December 2009|Latest]]) |
| If you have any questions or problems with the installation or administration of XFS, you can send email to [mailto:xfs@oss.sgi.com xfs@oss.sgi.com]. Note that this address is a public mailing list; please search the [http://oss.sgi.com/archives/xfs list archive] to see if your question has been answered previously.
| | * [[XFS status update for 2008]] ([[XFS_status_update_for_2008#XFS status update for December 2008|Latest]]) |
| | | * [[OLD_News|XFS status update before 2008]] |
| To report any bugs you encounter in XFS, use the [http://oss.sgi.com/bugzilla/ SGI Bugzilla] database.
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| == <font face="ARIAL NARROW,HELVETICA"> Recent News </font> ==
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> August-2006 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> Added the paper "High Bandwidth Filesystems on Large Systems" which was presented at the Ottawa Linux Symposium in July 2006. </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> July-2006 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> Several bulkstat related performance improvements, mostly improving DMAPI scans for filesystems with many millions of inodes, but also generic readahead improvements that will help other bulkstat users (e.g. xfsdump and quota). </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> July-2006 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> SLES10 is released, with full XFS and DMAPI support. </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> June-2006 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> First round of xfs_repair(8) performance improvements, and buffer/inode caching now done in libxfs in preparation for a multi-threaded version of xfs_repair at a later date. </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> May-2006 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> Additional inheritable inode flag (nodefrag) to allow specified inodes to be skipped by xfs_fsr(8). </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> May-2006 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> Updated the [http://oss.sgi.com/projects/xfs/faq.html#wcache FAQ] to discuss device write barriers. </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> Mar-2006 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> Incore extent management rework, more efficiently using memory when working with files with large numbers of extents. </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> Feb-2006 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> Per-CPU superblock accounting, improving buffered I/O throughput significantly for parallel I/O workloads. </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> Dec-2005 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> Rework the page writeout code paths within XFS to make better use of advances in 2.6 kernels (page clustering and larger block I/O requests). </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> Dec-2005 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> SLES9 Service Pack 3 released with next set of XFS updates. </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> Nov-2005 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> Support for block layer write barriers, allowing devices to be used with their write cache enabled (2.6+ kernels). </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> Nov-2005 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> Preferred extent size allocator hint for the B+ tree allocator. </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> Sep-2005 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> Support for inline extended attribute format 2, which significantly improves performance when using extended attributes. Driven by needs of the Samba folks for Samba version 4, but also helpful to many other people. </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> Jun-2005 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> Added support for project quota, and the ability to inherit project identifiers. Provides the mechanism for implementing a form of directory tree quota. </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> Jun-2005 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> Merged all XFS fixes since SP1 into SLES9 SP2. Thanks Andreas! </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> Jun-2005 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> [http://people.freebsd.org/%7Erodrigc/xfs/ XFS for FreeBSD] website announced (an independent porting effort not sponsored by SGI), supported by FreeBSD developers Craig Rodrigues and Alexander Kabaev. </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> Jan-2005 </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> Support use of 64 bit inode numbers with NFS. </font>
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| | bgcolor="#88ee88" valign="top" | <font face="Helvetica, Arial"> [Before-2005] </font>
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| | bgcolor="#99cccc" valign="top" | <font face="Helvetica, Arial"> [http://oss.sgi.com/projects/xfs/news.html Older news...] </font>
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| == <font face="ARIAL NARROW,HELVETICA"> Features </font> ==
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| The XFS filesystem provides the following major features: <br />
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| * '''Quick Recovery ''' | |
| The XFS journaling technology allows it to restart very quickly after an unexpected interruption, regardless of the number of files it is managing. Traditional filesystems must do special filesystem checks after an interruption, which can take many hours to complete. The XFS journaling avoids these lengthy filesystem checks.
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| * '''Fast Transactions'''
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| The XFS filesystem provides the advantages of journaling while minimizing the performance impact of journaling on read and write data transactions. Its journaling structures and algorithms are tuned to log the transactions rapidly.
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| XFS uses efficient tree structures for fast searches and rapid space allocation. XFS continues to deliver rapid response times, even for directories with tens of thousands of entries.
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| * '''Massive Scalability'''
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| XFS is a full 64-bit filesystem, and thus is capable of handling filesystems as large as a million terabytes.
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| 2<sup>63</sup> = 9 x 10<sup>18</sup> = 9 exabytes
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| A million terabytes is thousands of times larger than most large filesystems in use today. This may seem to be an extremely large address space, but it is needed to plan for the exponential disk density improvements observed in the storage industry in recent years. As disk capacity grows, not only does the address space need to be sufficiently large, but the structures and algorithms need to scale. XFS is ready today with the technologies needed for this scalability.
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| XFS also continues to evolve to match the capabilities of the hardware it is being deployed on. Efficiency when dealing with large amounts (terabytes) of main memory and hence large numbers of active files and large amounts of cached file data are areas demanding continual improvements. Extending XFS to improve performance on large NUMA machines is also an area of active research and development.
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| * '''Efficient Allocations''' | |
| XFS implements extremely sophisticated space management techniques. Efficiency in space management has been achieved through the use of variable sized extents, rather than the simple single-block-at-a-time mechanism of many other filesystems. XFS was the first filesystem to implement delayed space allocation for buffered writes, supports direct I/O, provides an optional realtime allocator, and is able to align allocations based on the geometry of the underlying storage device. The XFS allocator performs admirably in the presence of multiple parallel writers, and is renowned for its resistance to space fragmentation under such conditions.
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| * '''Excellent Bandwidth'''
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| XFS is capable of delivering very close to the raw I/O performance that the underlying hardware can provide. XFS has proven scalability on SGI Altix systems of multiple gigabytes-per-second on multiple terabyte filesystems.
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| == <font face="ARIAL NARROW,HELVETICA"> Technical Specifications </font> ==
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| '''Technology'''
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| Journaled 64-bit filesystem with guaranteed filesystem consistency.
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| '''Availability'''
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| XFS is available for Linux 2.4 and later Linux kernels.
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| '''Online Administration'''
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| XFS supports filesystem growth for mounted volumes, allows filesystem "freeze" and "thaw" operations to support volume level snapshots, and provides an online file defragmentation utility.
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| '''Quotas'''
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| XFS supports user and group quotas. XFS considers quota information as filesystem metadata and uses journaling to avoid the need for lengthy quota consistency checks after a crash. Project quota are now also supported, and these can be used to provide a form of directory tree quota.
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| '''Extended Attributes'''
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| XFS implements fully journaled extended attributes. An extended attribute is a name/value pair associated with a file. Attributes can be attached to all types of inodes: regular files, directories, symbolic links, device nodes, and so forth. Attribute values can contain up to 64KB of arbitrary binary data. XFS implements three attribute namespaces: a user namespace available to all users, protected by the normal file permissions; a system namespace, accessible only to privileged users; and a security namespace, used by security modules (SELinux). The system namespace can be used for protected filesystem meta-data such as access control lists (ACLs) and hierarchical storage manager (HSM) file migration status.
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| '''POSIX Access Control Lists (ACLs)'''
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| XFS supports the ACL semantics and interfaces described in the draft POSIX 1003.1e standard.
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| '''Maximum File Size'''
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| For Linux 2.4, the maximum accessible file offset is 16TB on 4K page size and 64TB on 16K page size. For Linux 2.6, when using 64 bit addressing in the block devices layer (CONFIG_LBD), file size limit increases to 9 million terabytes (or the device limits).
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| '''Maximum Filesystem Size'''
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| For Linux 2.4, 2 TB. For Linux 2.6 and beyond, when using 64 bit addressing in the block devices layer (CONFIG_LBD) and a 64 bit platform, filesystem size limit increases to 9 million terabytes (or the device limits). For these later kernels on 32 bit platforms, 16TB is the current limit even with 64 bit addressing enabled in the block layer.
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| '''Filesystem Block Size'''
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| The minimum filesystem block size is 512 bytes. The maximum filesystem block size is the page size of the kernel, which is 4K on x86 architecture and is set as a kernel compile option on the IA64 architecture (up to 64 kilobyte pages). So, XFS supports filesystem block sizes up to 64 kilobytes (from 512 bytes, in powers of 2), when the kernel page size allows it.
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| Filesystem extents (contiguous data) are configurable at file creation time using xfsctl(3) and are multiples of the filesystem block size. Individual extents can be up to 4 GB in size.
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| '''Physical Disk Sector Sizes Supported'''
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| 512 bytes through to 32 kilobytes (in powers of 2), with the caveat that the sector size must be less than or equal to the filesystem blocksize.
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| '''NFS Compatibility '''
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| With NFS version 3, 64-bit filesystems can be exported to other systems that support the NFS V3 protocol. Systems that use NFS V2 protocol may access XFS filesystems within the 32-bit limit imposed by the protocol.
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| '''Windows Compatibility'''
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| SGI uses the Open Source Samba server to export XFS filesystems to Microsoft Windows systems. Samba speaks the SMB (Server Message Block) and CIFS (Common Internet File System) protocols.
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| '''Backup/Restore'''
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| xfsdump and xfsrestore can be used for backup and restore of XFS file systems to local/remote SCSI tapes or files. It supports dumping of extended attributes and quota information. As the xfsdump format has been preserved and is now endian neutral, dumps created on one platform can be restored onto an XFS filesystem on another (different architectures, and even different operating systems - IRIX to Linux, and vice-versa).
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| '''Support for Hierarchical Storage'''
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| The Data Management API (DMAPI/XDSM) allows implementation of hierarchical storage management software with no kernel modifications as well as high-performance dump programs without requiring "raw" access to the disk and knowledge of filesystem structures.
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| '''Optional Realtime Allocator'''
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| XFS supports the notion of a "realtime subvolume" - a separate area of disk space where only file data is stored. Space on this subvolume is managed using the realtime allocator (as opposed to the default, B+ tree space allocator). The realtime subvolume is designed to provide very deterministic data rates suitable for media streaming applications.
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