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