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1 | OCFS2 filesystem |
2 | ================== |
3 | OCFS2 is a general purpose extent based shared disk cluster file |
4 | system with many similarities to ext3. It supports 64 bit inode |
5 | numbers, and has automatically extending metadata groups which may |
6 | also make it attractive for non-clustered use. |
7 | |
8 | You'll want to install the ocfs2-tools package in order to at least |
9 | get "mount.ocfs2" and "ocfs2_hb_ctl". |
10 | |
11 | Project web page: http://oss.oracle.com/projects/ocfs2 |
12 | Tools web page: http://oss.oracle.com/projects/ocfs2-tools |
13 | OCFS2 mailing lists: http://oss.oracle.com/projects/ocfs2/mailman/ |
14 | |
15 | All code copyright 2005 Oracle except when otherwise noted. |
16 | |
17 | CREDITS: |
18 | Lots of code taken from ext3 and other projects. |
19 | |
20 | Authors in alphabetical order: |
21 | Joel Becker <joel.becker@oracle.com> |
22 | Zach Brown <zach.brown@oracle.com> |
23 | Mark Fasheh <mfasheh@suse.com> |
24 | Kurt Hackel <kurt.hackel@oracle.com> |
25 | Tao Ma <tao.ma@oracle.com> |
26 | Sunil Mushran <sunil.mushran@oracle.com> |
27 | Manish Singh <manish.singh@oracle.com> |
28 | Tiger Yang <tiger.yang@oracle.com> |
29 | |
30 | Caveats |
31 | ======= |
32 | Features which OCFS2 does not support yet: |
33 | - Directory change notification (F_NOTIFY) |
34 | - Distributed Caching (F_SETLEASE/F_GETLEASE/break_lease) |
35 | |
36 | Mount options |
37 | ============= |
38 | |
39 | OCFS2 supports the following mount options: |
40 | (*) == default |
41 | |
42 | barrier=1 This enables/disables barriers. barrier=0 disables it, |
43 | barrier=1 enables it. |
44 | errors=remount-ro(*) Remount the filesystem read-only on an error. |
45 | errors=panic Panic and halt the machine if an error occurs. |
46 | intr (*) Allow signals to interrupt cluster operations. |
47 | nointr Do not allow signals to interrupt cluster |
48 | operations. |
49 | noatime Do not update access time. |
50 | relatime(*) Update atime if the previous atime is older than |
51 | mtime or ctime |
52 | strictatime Always update atime, but the minimum update interval |
53 | is specified by atime_quantum. |
54 | atime_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. |
58 | data=ordered (*) All data are forced directly out to the main file |
59 | system prior to its metadata being committed to the |
60 | journal. |
61 | data=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. |
64 | preferred_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. |
67 | commit=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. |
78 | localalloc=8(*) Allows custom localalloc size in MB. If the value is too |
79 | large, the fs will silently revert it to the default. |
80 | localflocks This disables cluster aware flock. |
81 | inode64 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. |
85 | user_xattr (*) Enables Extended User Attributes. |
86 | nouser_xattr Disables Extended User Attributes. |
87 | acl Enables POSIX Access Control Lists support. |
88 | noacl (*) Disables POSIX Access Control Lists support. |
89 | resv_level=2 (*) Set how aggressive allocation reservations will be. |
90 | Valid values are between 0 (reservations off) to 8 |
91 | (maximum space for reservations). |
92 | dir_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. |
96 | coherency=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. |
100 | coherency=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. |
103 |
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