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1OCFS2 filesystem
2==================
3OCFS2 is a general purpose extent based shared disk cluster file
4system with many similarities to ext3. It supports 64 bit inode
5numbers, and has automatically extending metadata groups which may
6also make it attractive for non-clustered use.
7
8You'll want to install the ocfs2-tools package in order to at least
9get "mount.ocfs2" and "ocfs2_hb_ctl".
10
11Project web page: http://ocfs2.wiki.kernel.org
12Tools git tree: https://github.com/markfasheh/ocfs2-tools
13OCFS2 mailing lists: http://oss.oracle.com/projects/ocfs2/mailman/
14
15All code copyright 2005 Oracle except when otherwise noted.
16
17CREDITS:
18Lots of code taken from ext3 and other projects.
19
20Authors in alphabetical order:
21Joel Becker <joel.becker@oracle.com>
22Zach Brown <zach.brown@oracle.com>
23Mark Fasheh <mfasheh@suse.com>
24Kurt Hackel <kurt.hackel@oracle.com>
25Tao Ma <tao.ma@oracle.com>
26Sunil Mushran <sunil.mushran@oracle.com>
27Manish Singh <manish.singh@oracle.com>
28Tiger Yang <tiger.yang@oracle.com>
29
30Caveats
31=======
32Features which OCFS2 does not support yet:
33 - Directory change notification (F_NOTIFY)
34 - Distributed Caching (F_SETLEASE/F_GETLEASE/break_lease)
35
36Mount options
37=============
38
39OCFS2 supports the following mount options:
40(*) == default
41
42barrier=1 This enables/disables barriers. barrier=0 disables it,
43 barrier=1 enables it.
44errors=remount-ro(*) Remount the filesystem read-only on an error.
45errors=panic Panic and halt the machine if an error occurs.
46intr (*) Allow signals to interrupt cluster operations.
47nointr Do not allow signals to interrupt cluster
48 operations.
49noatime Do not update access time.
50relatime(*) Update atime if the previous atime is older than
51 mtime or ctime
52strictatime Always update atime, but the minimum update interval
53 is specified by atime_quantum.
54atime_quantum=60(*) OCFS2 will not update atime unless this number
55 of seconds has passed since the last update.
56 Set to zero to always update atime. This option need
57 work with strictatime.
58data=ordered (*) All data are forced directly out to the main file
59 system prior to its metadata being committed to the
60 journal.
61data=writeback Data ordering is not preserved, data may be written
62 into the main file system after its metadata has been
63 committed to the journal.
64preferred_slot=0(*) During mount, try to use this filesystem slot first. If
65 it is in use by another node, the first empty one found
66 will be chosen. Invalid values will be ignored.
67commit=nrsec (*) Ocfs2 can be told to sync all its data and metadata
68 every 'nrsec' seconds. The default value is 5 seconds.
69 This means that if you lose your power, you will lose
70 as much as the latest 5 seconds of work (your
71 filesystem will not be damaged though, thanks to the
72 journaling). This default value (or any low value)
73 will hurt performance, but it's good for data-safety.
74 Setting it to 0 will have the same effect as leaving
75 it at the default (5 seconds).
76 Setting it to very large values will improve
77 performance.
78localalloc=8(*) Allows custom localalloc size in MB. If the value is too
79 large, the fs will silently revert it to the default.
80localflocks This disables cluster aware flock.
81inode64 Indicates that Ocfs2 is allowed to create inodes at
82 any location in the filesystem, including those which
83 will result in inode numbers occupying more than 32
84 bits of significance.
85user_xattr (*) Enables Extended User Attributes.
86nouser_xattr Disables Extended User Attributes.
87acl Enables POSIX Access Control Lists support.
88noacl (*) Disables POSIX Access Control Lists support.
89resv_level=2 (*) Set how aggressive allocation reservations will be.
90 Valid values are between 0 (reservations off) to 8
91 (maximum space for reservations).
92dir_resv_level= (*) By default, directory reservations will scale with file
93 reservations - users should rarely need to change this
94 value. If allocation reservations are turned off, this
95 option will have no effect.
96coherency=full (*) Disallow concurrent O_DIRECT writes, cluster inode
97 lock will be taken to force other nodes drop cache,
98 therefore full cluster coherency is guaranteed even
99 for O_DIRECT writes.
100coherency=buffered Allow concurrent O_DIRECT writes without EX lock among
101 nodes, which gains high performance at risk of getting
102 stale data on other nodes.
103journal_async_commit Commit block can be written to disk without waiting
104 for descriptor blocks. If enabled older kernels cannot
105 mount the device. This will enable 'journal_checksum'
106 internally.
1OCFS2 filesystem
2==================
3OCFS2 is a general purpose extent based shared disk cluster file
4system with many similarities to ext3. It supports 64 bit inode
5numbers, and has automatically extending metadata groups which may
6also make it attractive for non-clustered use.
7
8You'll want to install the ocfs2-tools package in order to at least
9get "mount.ocfs2" and "ocfs2_hb_ctl".
10
11Project web page: http://oss.oracle.com/projects/ocfs2
12Tools web page: http://oss.oracle.com/projects/ocfs2-tools
13OCFS2 mailing lists: http://oss.oracle.com/projects/ocfs2/mailman/
14
15All code copyright 2005 Oracle except when otherwise noted.
16
17CREDITS:
18Lots of code taken from ext3 and other projects.
19
20Authors in alphabetical order:
21Joel Becker <joel.becker@oracle.com>
22Zach Brown <zach.brown@oracle.com>
23Mark Fasheh <mfasheh@suse.com>
24Kurt Hackel <kurt.hackel@oracle.com>
25Tao Ma <tao.ma@oracle.com>
26Sunil Mushran <sunil.mushran@oracle.com>
27Manish Singh <manish.singh@oracle.com>
28Tiger Yang <tiger.yang@oracle.com>
29
30Caveats
31=======
32Features which OCFS2 does not support yet:
33 - Directory change notification (F_NOTIFY)
34 - Distributed Caching (F_SETLEASE/F_GETLEASE/break_lease)
35
36Mount options
37=============
38
39OCFS2 supports the following mount options:
40(*) == default
41
42barrier=1 This enables/disables barriers. barrier=0 disables it,
43 barrier=1 enables it.
44errors=remount-ro(*) Remount the filesystem read-only on an error.
45errors=panic Panic and halt the machine if an error occurs.
46intr (*) Allow signals to interrupt cluster operations.
47nointr Do not allow signals to interrupt cluster
48 operations.
49noatime Do not update access time.
50relatime(*) Update atime if the previous atime is older than
51 mtime or ctime
52strictatime Always update atime, but the minimum update interval
53 is specified by atime_quantum.
54atime_quantum=60(*) OCFS2 will not update atime unless this number
55 of seconds has passed since the last update.
56 Set to zero to always update atime. This option need
57 work with strictatime.
58data=ordered (*) All data are forced directly out to the main file
59 system prior to its metadata being committed to the
60 journal.
61data=writeback Data ordering is not preserved, data may be written
62 into the main file system after its metadata has been
63 committed to the journal.
64preferred_slot=0(*) During mount, try to use this filesystem slot first. If
65 it is in use by another node, the first empty one found
66 will be chosen. Invalid values will be ignored.
67commit=nrsec (*) Ocfs2 can be told to sync all its data and metadata
68 every 'nrsec' seconds. The default value is 5 seconds.
69 This means that if you lose your power, you will lose
70 as much as the latest 5 seconds of work (your
71 filesystem will not be damaged though, thanks to the
72 journaling). This default value (or any low value)
73 will hurt performance, but it's good for data-safety.
74 Setting it to 0 will have the same effect as leaving
75 it at the default (5 seconds).
76 Setting it to very large values will improve
77 performance.
78localalloc=8(*) Allows custom localalloc size in MB. If the value is too
79 large, the fs will silently revert it to the default.
80localflocks This disables cluster aware flock.
81inode64 Indicates that Ocfs2 is allowed to create inodes at
82 any location in the filesystem, including those which
83 will result in inode numbers occupying more than 32
84 bits of significance.
85user_xattr (*) Enables Extended User Attributes.
86nouser_xattr Disables Extended User Attributes.
87acl Enables POSIX Access Control Lists support.
88noacl (*) Disables POSIX Access Control Lists support.
89resv_level=2 (*) Set how aggressive allocation reservations will be.
90 Valid values are between 0 (reservations off) to 8
91 (maximum space for reservations).
92dir_resv_level= (*) By default, directory reservations will scale with file
93 reservations - users should rarely need to change this
94 value. If allocation reservations are turned off, this
95 option will have no effect.
96coherency=full (*) Disallow concurrent O_DIRECT writes, cluster inode
97 lock will be taken to force other nodes drop cache,
98 therefore full cluster coherency is guaranteed even
99 for O_DIRECT writes.
100coherency=buffered Allow concurrent O_DIRECT writes without EX lock among
101 nodes, which gains high performance at risk of getting
102 stale data on other nodes.