| 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://ocfs2.wiki.kernel.org |
| Tools git tree: https://github.com/markfasheh/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. |
| journal_async_commit Commit block can be written to disk without waiting |
| for descriptor blocks. If enabled older kernels cannot |
| mount the device. This will enable 'journal_checksum' |
| internally. |
