OCFS2

The Oracle Cluster File System (OCFS, in its second version OCFS2) is a shared disk file system developed by Oracle Corporation and released under the GNU General Public License. The first version of OCFS was developed with the main focus to accommodate Oracle's database management system that used cluster computing. Because of that it was not a POSIX-compliant file system. With version 2 the POSIX features were included.

OCFS2
Developer(s)Oracle Corporation
Full nameOracle Cluster file System
IntroducedMarch 2006 with Linux 2.6.16
Limits
Max volume size4 PB (OCFS2)[1]
Max file size4 PB (OCFS2)[1]
Max filename length255 bytes
Allowed filename
characters		All bytes except NUL and '/'
Features
Dates recordedmodification (mtime), attribute modification (ctime), access (atime)
File system
permissions		Unix permissions, ACLs and arbitrary security attributes (Linux 2.6 and later)
Transparent
compression		No
Transparent
encryption		No
Data deduplicationNo
Copy-on-writeYes
Other
Supported
operating systems		Linux

OCFS2 (version 2) was integrated into the version 2.6.16 of Linux kernel. Initially, it was marked as "experimental" (Alpha-test) code. This restriction was removed in Linux version 2.6.19. With kernel version 2.6.29 in late 2008, more features were included into ocfs2, such as access control lists and quotas.[2][3]

OCFS2 used a distributed lock manager which resembles the OpenVMS DLM but is much simpler.[4] Oracle announced version 1.6 in November 2010 which included a copy on write feature called reflink.[5]

See also

Notes and references
  1. Limited to 16TiB before 2.6.28 since it used the Linux JBD. JBD2 removes the limit.
  2. Mark Fasheh (December 19, 2008). "Ocfs2 patches for merge window batch 1/3". Linux Kernel Mailing List. Retrieved October 24, 2016.
  3. Mark Fasheh (December 22, 2008). "Ocfs2 patches for merge window batch 2/3". Linux Kernel Mailing List. Retrieved October 24, 2016.
  4. Jonathan Corbet (May 24, 2005). "The OCFS2 filesystem". LWN.net. Retrieved October 24, 2016.
  5. John Margaglione (November 30, 2010). "What's new in Oracle Linux Part 1: OCFS2 1.6 REFLINKs". Oracle. Archived from the original on May 10, 2017. Retrieved May 10, 2017.
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