1 .. SPDX-License-Identifier: GPL-2.0 2 3 ================ 4 OCFS2 filesystem 5 ================ 6 7 OCFS2 is a general purpose extent based shared disk cluster file 8 system with many similarities to ext3. It supports 64 bit inode 9 numbers, and has automatically extending metadata groups which may 10 also make it attractive for non-clustered use. 11 12 You'll want to install the ocfs2-tools package in order to at least 13 get "mount.ocfs2" and "ocfs2_hb_ctl". 14 15 Project web page: http://ocfs2.wiki.kernel.org 16 Tools git tree: https://github.com/markfasheh/ocfs2-tools 17 OCFS2 mailing lists: https://subspace.kernel.org/lists.linux.dev.html 18 19 All code copyright 2005 Oracle except when otherwise noted. 20 21 Credits 22 ======= 23 24 Lots of code taken from ext3 and other projects. 25 26 Authors in alphabetical order: 27 28 - Joel Becker <joel.becker@oracle.com> 29 - Zach Brown <zach.brown@oracle.com> 30 - Mark Fasheh <mfasheh@suse.com> 31 - Kurt Hackel <kurt.hackel@oracle.com> 32 - Tao Ma <tao.ma@oracle.com> 33 - Sunil Mushran <sunil.mushran@oracle.com> 34 - Manish Singh <manish.singh@oracle.com> 35 - Tiger Yang <tiger.yang@oracle.com> 36 37 Caveats 38 ======= 39 Features which OCFS2 does not support yet: 40 41 - Directory change notification (F_NOTIFY) 42 - Distributed Caching (F_SETLEASE/F_GETLEASE/break_lease) 43 44 Mount options 45 ============= 46 47 OCFS2 supports the following mount options: 48 49 (*) == default 50 51 ======================= ======================================================== 52 barrier=1 This enables/disables barriers. barrier=0 disables it, 53 barrier=1 enables it. 54 errors=remount-ro(*) Remount the filesystem read-only on an error. 55 errors=panic Panic and halt the machine if an error occurs. 56 intr (*) Allow signals to interrupt cluster operations. 57 nointr Do not allow signals to interrupt cluster 58 operations. 59 noatime Do not update access time. 60 relatime(*) Update atime if the previous atime is older than 61 mtime or ctime 62 strictatime Always update atime, but the minimum update interval 63 is specified by atime_quantum. 64 atime_quantum=60(*) OCFS2 will not update atime unless this number 65 of seconds has passed since the last update. 66 Set to zero to always update atime. This option need 67 work with strictatime. 68 data=ordered (*) All data are forced directly out to the main file 69 system prior to its metadata being committed to the 70 journal. 71 data=writeback Data ordering is not preserved, data may be written 72 into the main file system after its metadata has been 73 committed to the journal. 74 preferred_slot=0(*) During mount, try to use this filesystem slot first. If 75 it is in use by another node, the first empty one found 76 will be chosen. Invalid values will be ignored. 77 commit=nrsec (*) Ocfs2 can be told to sync all its data and metadata 78 every 'nrsec' seconds. The default value is 5 seconds. 79 This means that if you lose your power, you will lose 80 as much as the latest 5 seconds of work (your 81 filesystem will not be damaged though, thanks to the 82 journaling). This default value (or any low value) 83 will hurt performance, but it's good for data-safety. 84 Setting it to 0 will have the same effect as leaving 85 it at the default (5 seconds). 86 Setting it to very large values will improve 87 performance. 88 localalloc=8(*) Allows custom localalloc size in MB. If the value is too 89 large, the fs will silently revert it to the default. 90 localflocks This disables cluster aware flock. 91 inode64 Indicates that Ocfs2 is allowed to create inodes at 92 any location in the filesystem, including those which 93 will result in inode numbers occupying more than 32 94 bits of significance. 95 user_xattr (*) Enables Extended User Attributes. 96 nouser_xattr Disables Extended User Attributes. 97 acl Enables POSIX Access Control Lists support. 98 noacl (*) Disables POSIX Access Control Lists support. 99 resv_level=2 (*) Set how aggressive allocation reservations will be. 100 Valid values are between 0 (reservations off) to 8 101 (maximum space for reservations). 102 dir_resv_level= (*) By default, directory reservations will scale with file 103 reservations - users should rarely need to change this 104 value. If allocation reservations are turned off, this 105 option will have no effect. 106 coherency=full (*) Disallow concurrent O_DIRECT writes, cluster inode 107 lock will be taken to force other nodes drop cache, 108 therefore full cluster coherency is guaranteed even 109 for O_DIRECT writes. 110 coherency=buffered Allow concurrent O_DIRECT writes without EX lock among 111 nodes, which gains high performance at risk of getting 112 stale data on other nodes. 113 journal_async_commit Commit block can be written to disk without waiting 114 for descriptor blocks. If enabled older kernels cannot 115 mount the device. This will enable 'journal_checksum' 116 internally. 117 ======================= ========================================================
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