1.. SPDX-License-Identifier: GPL-2.0 2 3================ 4OCFS2 filesystem 5================ 6 7OCFS2 is a general purpose extent based shared disk cluster file 8system with many similarities to ext3. It supports 64 bit inode 9numbers, and has automatically extending metadata groups which may 10also make it attractive for non-clustered use. 11 12You'll want to install the ocfs2-tools package in order to at least 13get "mount.ocfs2" and "ocfs2_hb_ctl". 14 15Project web page: http://ocfs2.wiki.kernel.org 16Tools git tree: https://github.com/markfasheh/ocfs2-tools 17OCFS2 mailing lists: https://subspace.kernel.org/lists.linux.dev.html 18 19All code copyright 2005 Oracle except when otherwise noted. 20 21Credits 22======= 23 24Lots of code taken from ext3 and other projects. 25 26Authors 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 37Caveats 38======= 39Features which OCFS2 does not support yet: 40 41 - Directory change notification (F_NOTIFY) 42 - Distributed Caching (F_SETLEASE/F_GETLEASE/break_lease) 43 44Mount options 45============= 46 47OCFS2 supports the following mount options: 48 49(*) == default 50 51======================= ======================================================== 52barrier=1 This enables/disables barriers. barrier=0 disables it, 53 barrier=1 enables it. 54errors=remount-ro(*) Remount the filesystem read-only on an error. 55errors=panic Panic and halt the machine if an error occurs. 56intr (*) Allow signals to interrupt cluster operations. 57nointr Do not allow signals to interrupt cluster 58 operations. 59noatime Do not update access time. 60relatime(*) Update atime if the previous atime is older than 61 mtime or ctime 62strictatime Always update atime, but the minimum update interval 63 is specified by atime_quantum. 64atime_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. 68data=ordered (*) All data are forced directly out to the main file 69 system prior to its metadata being committed to the 70 journal. 71data=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. 74preferred_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. 77commit=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. 88localalloc=8(*) Allows custom localalloc size in MB. If the value is too 89 large, the fs will silently revert it to the default. 90localflocks This disables cluster aware flock. 91inode64 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. 95user_xattr (*) Enables Extended User Attributes. 96nouser_xattr Disables Extended User Attributes. 97acl Enables POSIX Access Control Lists support. 98noacl (*) Disables POSIX Access Control Lists support. 99resv_level=2 (*) Set how aggressive allocation reservations will be. 100 Valid values are between 0 (reservations off) to 8 101 (maximum space for reservations). 102dir_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. 106coherency=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. 110coherency=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. 113journal_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======================= ======================================================== 118