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- OCFS2 filesystem
- ==================
- OCFS2 is a general purpose extent based shared disk cluster file
- system with many similarities to ext3. It supports 64 bit inode
- numbers, and has automatically extending metadata groups which may
- also make it attractive for non-clustered use.
- You'll want to install the ocfs2-tools package in order to at least
- get "mount.ocfs2" and "ocfs2_hb_ctl".
- Project web page: http://oss.oracle.com/projects/ocfs2
- Tools web page: http://oss.oracle.com/projects/ocfs2-tools
- OCFS2 mailing lists: http://oss.oracle.com/projects/ocfs2/mailman/
- All code copyright 2005 Oracle except when otherwise noted.
- CREDITS:
- Lots of code taken from ext3 and other projects.
- Authors in alphabetical order:
- Joel Becker <joel.becker@oracle.com>
- Zach Brown <zach.brown@oracle.com>
- Mark Fasheh <mfasheh@suse.com>
- Kurt Hackel <kurt.hackel@oracle.com>
- Tao Ma <tao.ma@oracle.com>
- Sunil Mushran <sunil.mushran@oracle.com>
- Manish Singh <manish.singh@oracle.com>
- Tiger Yang <tiger.yang@oracle.com>
- Caveats
- =======
- Features which OCFS2 does not support yet:
- - Directory change notification (F_NOTIFY)
- - Distributed Caching (F_SETLEASE/F_GETLEASE/break_lease)
- Mount options
- =============
- OCFS2 supports the following mount options:
- (*) == default
- barrier=1 This enables/disables barriers. barrier=0 disables it,
- barrier=1 enables it.
- errors=remount-ro(*) Remount the filesystem read-only on an error.
- errors=panic Panic and halt the machine if an error occurs.
- intr (*) Allow signals to interrupt cluster operations.
- nointr Do not allow signals to interrupt cluster
- operations.
- noatime Do not update access time.
- relatime(*) Update atime if the previous atime is older than
- mtime or ctime
- strictatime Always update atime, but the minimum update interval
- is specified by atime_quantum.
- atime_quantum=60(*) OCFS2 will not update atime unless this number
- of seconds has passed since the last update.
- Set to zero to always update atime. This option need
- work with strictatime.
- data=ordered (*) All data are forced directly out to the main file
- system prior to its metadata being committed to the
- journal.
- data=writeback Data ordering is not preserved, data may be written
- into the main file system after its metadata has been
- committed to the journal.
- preferred_slot=0(*) During mount, try to use this filesystem slot first. If
- it is in use by another node, the first empty one found
- will be chosen. Invalid values will be ignored.
- commit=nrsec (*) Ocfs2 can be told to sync all its data and metadata
- every 'nrsec' seconds. The default value is 5 seconds.
- This means that if you lose your power, you will lose
- as much as the latest 5 seconds of work (your
- filesystem will not be damaged though, thanks to the
- journaling). This default value (or any low value)
- will hurt performance, but it's good for data-safety.
- Setting it to 0 will have the same effect as leaving
- it at the default (5 seconds).
- Setting it to very large values will improve
- performance.
- localalloc=8(*) Allows custom localalloc size in MB. If the value is too
- large, the fs will silently revert it to the default.
- localflocks This disables cluster aware flock.
- inode64 Indicates that Ocfs2 is allowed to create inodes at
- any location in the filesystem, including those which
- will result in inode numbers occupying more than 32
- bits of significance.
- user_xattr (*) Enables Extended User Attributes.
- nouser_xattr Disables Extended User Attributes.
- acl Enables POSIX Access Control Lists support.
- noacl (*) Disables POSIX Access Control Lists support.
- resv_level=2 (*) Set how aggressive allocation reservations will be.
- Valid values are between 0 (reservations off) to 8
- (maximum space for reservations).
- dir_resv_level= (*) By default, directory reservations will scale with file
- reservations - users should rarely need to change this
- value. If allocation reservations are turned off, this
- option will have no effect.
- coherency=full (*) Disallow concurrent O_DIRECT writes, cluster inode
- lock will be taken to force other nodes drop cache,
- therefore full cluster coherency is guaranteed even
- for O_DIRECT writes.
- coherency=buffered Allow concurrent O_DIRECT writes without EX lock among
- nodes, which gains high performance at risk of getting
- stale data on other nodes.
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