VERITAS File System

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The Veritas File System, (or VxFS, called JFS and OJFS in HP-UX ), is an extent-based file system that was the first commercial journaling file system. It was originally developed by VERITAS Software which merged with Symantec in 2005. Through an OEM agreement, VxFS is used as the primary filesystem of the HP-UX operating system, although HP-UX calls it JFS. A variant with on-line defragmentation and resize support is known as OJFS. It is also supported on AIX, Linux, Solaris, SINIX/Reliant UNIX and UnixWare. VxFS was originally developed for AT&T's Unix System Laboratories. VxFS is packaged as a part of the Veritas Storage Foundation (which also includes Veritas Volume Manager).

1 Layout versions
2 Parallel access mode
3 References
4 See also
5 External links

[edit] Layout versions

The on-disk layout of VxFS is versioned and upgradeable while the file system is mounted.

The version 5 on-disk layout of VxFS supports file systems up to 32 terabytes in size. Individual files can be up to 2 terabytes in size. Version 5 was introduced in VxFS 3.5.

The version 6 on-disk layout supports file systems and files up to 8 exabytes in size. Version 6 also introduced support for named streams/resource forks, for multiple underlying volumes, and for file change logs. Version 6 was introduced in VxFS 4.0.

The version 7 layout introduced in version 5.0 extends support for multiple volumes to permit Dynamic Storage Tiering. Dynamic Storage Tiering allows root users to move files among different volumes, allocate files to different volumes at file creation time based on policy, and independently recover volumes, without altering the namespace of the file system.

[edit] Parallel access mode

VxFS can run in single instance mode or in a parallel access/cluster file system mode. This latter mode allows for multiple servers (also known as cluster nodes) to simultaneously access the same file system. When run in this mode, VxFS is referred to as Veritas Cluster File System. Cluster File System provides cache coherency and POSIX compliance across nodes, so that data changes are atomically seen by all cluster nodes simultaneously. Because Cluster File System shares the same binaries and same on-disk layout as single instance VxFS, moving between cluster and single instance mode is straightforward.