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Diffstat (limited to 'Documentation/filesystems/xfs.txt')
| -rw-r--r-- | Documentation/filesystems/xfs.txt | 357 |
1 files changed, 266 insertions, 91 deletions
diff --git a/Documentation/filesystems/xfs.txt b/Documentation/filesystems/xfs.txt index c7d5d0c7067..5be51fd888b 100644 --- a/Documentation/filesystems/xfs.txt +++ b/Documentation/filesystems/xfs.txt @@ -18,42 +18,137 @@ Mount Options ============= When mounting an XFS filesystem, the following options are accepted. - - biosize=size - Sets the preferred buffered I/O size (default size is 64K). - "size" must be expressed as the logarithm (base2) of the - desired I/O size. - Valid values for this option are 14 through 16, inclusive - (i.e. 16K, 32K, and 64K bytes). On machines with a 4K - pagesize, 13 (8K bytes) is also a valid size. - The preferred buffered I/O size can also be altered on an - individual file basis using the ioctl(2) system call. - - ikeep/noikeep - When inode clusters are emptied of inodes, keep them around - on the disk (ikeep) - this is the traditional XFS behaviour - and is still the default for now. Using the noikeep option, - inode clusters are returned to the free space pool. +For boolean mount options, the names with the (*) suffix is the +default behaviour. + + allocsize=size + Sets the buffered I/O end-of-file preallocation size when + doing delayed allocation writeout (default size is 64KiB). + Valid values for this option are page size (typically 4KiB) + through to 1GiB, inclusive, in power-of-2 increments. + + The default behaviour is for dynamic end-of-file + preallocation size, which uses a set of heuristics to + optimise the preallocation size based on the current + allocation patterns within the file and the access patterns + to the file. Specifying a fixed allocsize value turns off + the dynamic behaviour. + + attr2 + noattr2 + The options enable/disable an "opportunistic" improvement to + be made in the way inline extended attributes are stored + on-disk. When the new form is used for the first time when + attr2 is selected (either when setting or removing extended + attributes) the on-disk superblock feature bit field will be + updated to reflect this format being in use. + + The default behaviour is determined by the on-disk feature + bit indicating that attr2 behaviour is active. If either + mount option it set, then that becomes the new default used + by the filesystem. + + CRC enabled filesystems always use the attr2 format, and so + will reject the noattr2 mount option if it is set. + + barrier (*) + nobarrier + Enables/disables the use of block layer write barriers for + writes into the journal and for data integrity operations. + This allows for drive level write caching to be enabled, for + devices that support write barriers. + + discard + nodiscard (*) + Enable/disable the issuing of commands to let the block + device reclaim space freed by the filesystem. This is + useful for SSD devices, thinly provisioned LUNs and virtual + machine images, but may have a performance impact. + + Note: It is currently recommended that you use the fstrim + application to discard unused blocks rather than the discard + mount option because the performance impact of this option + is quite severe. + + grpid/bsdgroups + nogrpid/sysvgroups (*) + These options define what group ID a newly created file + gets. When grpid is set, it takes the group ID of the + directory in which it is created; otherwise it takes the + fsgid of the current process, unless the directory has the + setgid bit set, in which case it takes the gid from the + parent directory, and also gets the setgid bit set if it is + a directory itself. + + filestreams + Make the data allocator use the filestreams allocation mode + across the entire filesystem rather than just on directories + configured to use it. + + ikeep + noikeep (*) + When ikeep is specified, XFS does not delete empty inode + clusters and keeps them around on disk. When noikeep is + specified, empty inode clusters are returned to the free + space pool. + + inode32 + inode64 (*) + When inode32 is specified, it indicates that XFS limits + inode creation to locations which will not result in inode + numbers with more than 32 bits of significance. + + When inode64 is specified, it indicates that XFS 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. + + inode32 is provided for backwards compatibility with older + systems and applications, since 64 bits inode numbers might + cause problems for some applications that cannot handle + large inode numbers. If applications are in use which do + not handle inode numbers bigger than 32 bits, the inode32 + option should be specified. + + + largeio + nolargeio (*) + If "nolargeio" is specified, the optimal I/O reported in + st_blksize by stat(2) will be as small as possible to allow + user applications to avoid inefficient read/modify/write + I/O. This is typically the page size of the machine, as + this is the granularity of the page cache. + + If "largeio" specified, a filesystem that was created with a + "swidth" specified will return the "swidth" value (in bytes) + in st_blksize. If the filesystem does not have a "swidth" + specified but does specify an "allocsize" then "allocsize" + (in bytes) will be returned instead. Otherwise the behaviour + is the same as if "nolargeio" was specified. logbufs=value - Set the number of in-memory log buffers. Valid numbers range - from 2-8 inclusive. - The default value is 8 buffers for filesystems with a - blocksize of 64K, 4 buffers for filesystems with a blocksize - of 32K, 3 buffers for filesystems with a blocksize of 16K - and 2 buffers for all other configurations. Increasing the - number of buffers may increase performance on some workloads - at the cost of the memory used for the additional log buffers - and their associated control structures. + Set the number of in-memory log buffers. Valid numbers + range from 2-8 inclusive. + + The default value is 8 buffers. + + If the memory cost of 8 log buffers is too high on small + systems, then it may be reduced at some cost to performance + on metadata intensive workloads. The logbsize option below + controls the size of each buffer and so is also relevant to + this case. logbsize=value - Set the size of each in-memory log buffer. - Size may be specified in bytes, or in kilobytes with a "k" suffix. - Valid sizes for version 1 and version 2 logs are 16384 (16k) and - 32768 (32k). Valid sizes for version 2 logs also include - 65536 (64k), 131072 (128k) and 262144 (256k). - The default value for machines with more than 32MB of memory - is 32768, machines with less memory use 16384 by default. + Set the size of each in-memory log buffer. The size may be + specified in bytes, or in kilobytes with a "k" suffix. + Valid sizes for version 1 and version 2 logs are 16384 (16k) + and 32768 (32k). Valid sizes for version 2 logs also + include 65536 (64k), 131072 (128k) and 262144 (256k). The + logbsize must be an integer multiple of the log + stripe unit configured at mkfs time. + + The default value for for version 1 logs is 32768, while the + default value for version 2 logs is MAX(32768, log_sunit). logdev=device and rtdev=device Use an external log (metadata journal) and/or real-time device. @@ -63,10 +158,10 @@ When mounting an XFS filesystem, the following options are accepted. section or contained within it. noalign - Data allocations will not be aligned at stripe unit boundaries. - - noatime - Access timestamps are not updated when a file is read. + Data allocations will not be aligned at stripe unit + boundaries. This is only relevant to filesystems created + with non-zero data alignment parameters (sunit, swidth) by + mkfs. norecovery The filesystem will be mounted without running log recovery. @@ -77,41 +172,86 @@ When mounting an XFS filesystem, the following options are accepted. the mount will fail. nouuid - Don't check for double mounted file systems using the file system uuid. - This is useful to mount LVM snapshot volumes. + Don't check for double mounted file systems using the file + system uuid. This is useful to mount LVM snapshot volumes, + and often used in combination with "norecovery" for mounting + read-only snapshots. - osyncisosync - Make O_SYNC writes implement true O_SYNC. WITHOUT this option, - Linux XFS behaves as if an "osyncisdsync" option is used, - which will make writes to files opened with the O_SYNC flag set - behave as if the O_DSYNC flag had been used instead. - This can result in better performance without compromising - data safety. - However if this option is not in effect, timestamp updates from - O_SYNC writes can be lost if the system crashes. - If timestamp updates are critical, use the osyncisosync option. - - quota/usrquota/uqnoenforce + noquota + Forcibly turns off all quota accounting and enforcement + within the filesystem. + + uquota/usrquota/uqnoenforce/quota User disk quota accounting enabled, and limits (optionally) - enforced. + enforced. Refer to xfs_quota(8) for further details. - grpquota/gqnoenforce + gquota/grpquota/gqnoenforce Group disk quota accounting enabled and limits (optionally) - enforced. + enforced. Refer to xfs_quota(8) for further details. + + pquota/prjquota/pqnoenforce + Project disk quota accounting enabled and limits (optionally) + enforced. Refer to xfs_quota(8) for further details. sunit=value and swidth=value - Used to specify the stripe unit and width for a RAID device or - a stripe volume. "value" must be specified in 512-byte block - units. - If this option is not specified and the filesystem was made on - a stripe volume or the stripe width or unit were specified for - the RAID device at mkfs time, then the mount system call will - restore the value from the superblock. For filesystems that - are made directly on RAID devices, these options can be used - to override the information in the superblock if the underlying - disk layout changes after the filesystem has been created. - The "swidth" option is required if the "sunit" option has been - specified, and must be a multiple of the "sunit" value. + Used to specify the stripe unit and width for a RAID device + or a stripe volume. "value" must be specified in 512-byte + block units. These options are only relevant to filesystems + that were created with non-zero data alignment parameters. + + The sunit and swidth parameters specified must be compatible + with the existing filesystem alignment characteristics. In + general, that means the only valid changes to sunit are + increasing it by a power-of-2 multiple. Valid swidth values + are any integer multiple of a valid sunit value. + + Typically the only time these mount options are necessary if + after an underlying RAID device has had it's geometry + modified, such as adding a new disk to a RAID5 lun and + reshaping it. + + swalloc + Data allocations will be rounded up to stripe width boundaries + when the current end of file is being extended and the file + size is larger than the stripe width size. + + wsync + When specified, all filesystem namespace operations are + executed synchronously. This ensures that when the namespace + operation (create, unlink, etc) completes, the change to the + namespace is on stable storage. This is useful in HA setups + where failover must not result in clients seeing + inconsistent namespace presentation during or after a + failover event. + + +Deprecated Mount Options +======================== + + delaylog/nodelaylog + Delayed logging is the only logging method that XFS supports + now, so these mount options are now ignored. + + Due for removal in 3.12. + + ihashsize=value + In memory inode hashes have been removed, so this option has + no function as of August 2007. Option is deprecated. + + Due for removal in 3.12. + + irixsgid + This behaviour is now controlled by a sysctl, so the mount + option is ignored. + + Due for removal in 3.12. + + osyncisdsync + osyncisosync + O_SYNC and O_DSYNC are fully supported, so there is no need + for these options any more. + + Due for removal in 3.12. sysctls ======= @@ -119,19 +259,24 @@ sysctls The following sysctls are available for the XFS filesystem: fs.xfs.stats_clear (Min: 0 Default: 0 Max: 1) - Setting this to "1" clears accumulated XFS statistics + Setting this to "1" clears accumulated XFS statistics in /proc/fs/xfs/stat. It then immediately resets to "0". - + fs.xfs.xfssyncd_centisecs (Min: 100 Default: 3000 Max: 720000) - The interval at which the xfssyncd thread flushes metadata - out to disk. This thread will flush log activity out, and - do some processing on unlinked inodes. + The interval at which the filesystem flushes metadata + out to disk and runs internal cache cleanup routines. - fs.xfs.xfsbufd_centisecs (Min: 50 Default: 100 Max: 3000) - The interval at which xfsbufd scans the dirty metadata buffers list. + fs.xfs.filestream_centisecs (Min: 1 Default: 3000 Max: 360000) + The interval at which the filesystem ages filestreams cache + references and returns timed-out AGs back to the free stream + pool. - fs.xfs.age_buffer_centisecs (Min: 100 Default: 1500 Max: 720000) - The age at which xfsbufd flushes dirty metadata buffers to disk. + fs.xfs.speculative_prealloc_lifetime + (Units: seconds Min: 1 Default: 300 Max: 86400) + The interval at which the background scanning for inodes + with unused speculative preallocation runs. The scan + removes unused preallocation from clean inodes and releases + the unused space back to the free pool. fs.xfs.error_level (Min: 0 Default: 3 Max: 11) A volume knob for error reporting when internal errors occur. @@ -143,9 +288,9 @@ The following sysctls are available for the XFS filesystem: XFS_ERRLEVEL_HIGH: 5 fs.xfs.panic_mask (Min: 0 Default: 0 Max: 127) - Causes certain error conditions to call BUG(). Value is a bitmask; + Causes certain error conditions to call BUG(). Value is a bitmask; AND together the tags which represent errors which should cause panics: - + XFS_NO_PTAG 0 XFS_PTAG_IFLUSH 0x00000001 XFS_PTAG_LOGRES 0x00000002 @@ -155,7 +300,7 @@ The following sysctls are available for the XFS filesystem: XFS_PTAG_SHUTDOWN_IOERROR 0x00000020 XFS_PTAG_SHUTDOWN_LOGERROR 0x00000040 - This option is intended for debugging only. + This option is intended for debugging only. fs.xfs.irix_symlink_mode (Min: 0 Default: 0 Max: 1) Controls whether symlinks are created with mode 0777 (default) @@ -164,25 +309,55 @@ The following sysctls are available for the XFS filesystem: fs.xfs.irix_sgid_inherit (Min: 0 Default: 0 Max: 1) Controls files created in SGID directories. If the group ID of the new file does not match the effective group - ID or one of the supplementary group IDs of the parent dir, the - ISGID bit is cleared if the irix_sgid_inherit compatibility sysctl + ID or one of the supplementary group IDs of the parent dir, the + ISGID bit is cleared if the irix_sgid_inherit compatibility sysctl is set. - fs.xfs.restrict_chown (Min: 0 Default: 1 Max: 1) - Controls whether unprivileged users can use chown to "give away" - a file to another user. + fs.xfs.inherit_sync (Min: 0 Default: 1 Max: 1) + Setting this to "1" will cause the "sync" flag set + by the xfs_io(8) chattr command on a directory to be + inherited by files in that directory. - fs.xfs.inherit_sync (Min: 0 Default: 1 Max 1) - Setting this to "1" will cause the "sync" flag set - by the chattr(1) command on a directory to be + fs.xfs.inherit_nodump (Min: 0 Default: 1 Max: 1) + Setting this to "1" will cause the "nodump" flag set + by the xfs_io(8) chattr command on a directory to be inherited by files in that directory. - fs.xfs.inherit_nodump (Min: 0 Default: 1 Max 1) - Setting this to "1" will cause the "nodump" flag set - by the chattr(1) command on a directory to be + fs.xfs.inherit_noatime (Min: 0 Default: 1 Max: 1) + Setting this to "1" will cause the "noatime" flag set + by the xfs_io(8) chattr command on a directory to be inherited by files in that directory. - fs.xfs.inherit_noatime (Min: 0 Default: 1 Max 1) - Setting this to "1" will cause the "noatime" flag set - by the chattr(1) command on a directory to be + fs.xfs.inherit_nosymlinks (Min: 0 Default: 1 Max: 1) + Setting this to "1" will cause the "nosymlinks" flag set + by the xfs_io(8) chattr command on a directory to be inherited by files in that directory. + + fs.xfs.inherit_nodefrag (Min: 0 Default: 1 Max: 1) + Setting this to "1" will cause the "nodefrag" flag set + by the xfs_io(8) chattr command on a directory to be + inherited by files in that directory. + + fs.xfs.rotorstep (Min: 1 Default: 1 Max: 256) + In "inode32" allocation mode, this option determines how many + files the allocator attempts to allocate in the same allocation + group before moving to the next allocation group. The intent + is to control the rate at which the allocator moves between + allocation groups when allocating extents for new files. + +Deprecated Sysctls +================== + + fs.xfs.xfsbufd_centisecs (Min: 50 Default: 100 Max: 3000) + Dirty metadata is now tracked by the log subsystem and + flushing is driven by log space and idling demands. The + xfsbufd no longer exists, so this syctl does nothing. + + Due for removal in 3.14. + + fs.xfs.age_buffer_centisecs (Min: 100 Default: 1500 Max: 720000) + Dirty metadata is now tracked by the log subsystem and + flushing is driven by log space and idling demands. The + xfsbufd no longer exists, so this syctl does nothing. + + Due for removal in 3.14. |