--- /dev/null
+.. SPDX-License-Identifier: GPL-2.0
+
+======================
+The SGI XFS Filesystem
+======================
+
+XFS is a high performance journaling filesystem which originated
+on the SGI IRIX platform. It is completely multi-threaded, can
+support large files and large filesystems, extended attributes,
+variable block sizes, is extent based, and makes extensive use of
+Btrees (directories, extents, free space) to aid both performance
+and scalability.
+
+Refer to the documentation at https://xfs.wiki.kernel.org/
+for further details. This implementation is on-disk compatible
+with the IRIX version of XFS.
+
+
+Mount Options
+=============
+
+When mounting an XFS filesystem, the following options are accepted.
+
+ 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 or 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 is 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.
+
+ discard or nodiscard (default)
+ 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 or nogrpid/sysvgroups (default)
+ 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 or noikeep (default)
+ 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 or inode64 (default)
+ 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 or nolargeio (default)
+ 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`` is 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.
+
+ 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. 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(8)** 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.
+ An XFS filesystem has up to three parts: a data section, a log
+ section, and a real-time section. The real-time section is
+ optional, and the log section can be separate from the data
+ section or contained within it.
+
+ noalign
+ 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(8)**.
+
+ norecovery
+ The filesystem will be mounted without running log recovery.
+ If the filesystem was not cleanly unmounted, it is likely to
+ be inconsistent when mounted in ``norecovery`` mode.
+ Some files or directories may not be accessible because of this.
+ Filesystems mounted ``norecovery`` must be mounted read-only or
+ 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,
+ and often used in combination with ``norecovery`` for mounting
+ read-only snapshots.
+
+ 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. Refer to **xfs_quota(8)** for further details.
+
+ gquota/grpquota/gqnoenforce
+ Group disk quota accounting enabled and limits (optionally)
+ 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. 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
+========================
+
+=========================== ================
+ Name Removal Schedule
+=========================== ================
+=========================== ================
+
+
+Removed Mount Options
+=====================
+
+=========================== =======
+ Name Removed
+=========================== =======
+ delaylog/nodelaylog v4.0
+ ihashsize v4.0
+ irixsgid v4.0
+ osyncisdsync/osyncisosync v4.0
+ barrier v4.19
+ nobarrier v4.19
+=========================== =======
+
+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
+ 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 filesystem flushes metadata
+ out to disk and runs internal cache cleanup routines.
+
+ 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.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.
+ This will generate detailed messages & backtraces for filesystem
+ shutdowns, for example. Current threshold values are:
+
+ XFS_ERRLEVEL_OFF: 0
+ XFS_ERRLEVEL_LOW: 1
+ XFS_ERRLEVEL_HIGH: 5
+
+ fs.xfs.panic_mask (Min: 0 Default: 0 Max: 256)
+ Causes certain error conditions to call BUG(). Value is a bitmask;
+ OR together the tags which represent errors which should cause panics:
+
+ XFS_NO_PTAG 0
+ XFS_PTAG_IFLUSH 0x00000001
+ XFS_PTAG_LOGRES 0x00000002
+ XFS_PTAG_AILDELETE 0x00000004
+ XFS_PTAG_ERROR_REPORT 0x00000008
+ XFS_PTAG_SHUTDOWN_CORRUPT 0x00000010
+ XFS_PTAG_SHUTDOWN_IOERROR 0x00000020
+ XFS_PTAG_SHUTDOWN_LOGERROR 0x00000040
+ XFS_PTAG_FSBLOCK_ZERO 0x00000080
+ XFS_PTAG_VERIFIER_ERROR 0x00000100
+
+ 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)
+ or whether their mode is affected by the umask (irix mode).
+
+ 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
+ is set.
+
+ 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_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_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_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
+==================
+
+None at present.
+
+
+Removed Sysctls
+===============
+
+ Name Removed
+ ---- -------
+ fs.xfs.xfsbufd_centisec v4.0
+ fs.xfs.age_buffer_centisecs v4.0
+
+
+Error handling
+==============
+
+XFS can act differently according to the type of error found during its
+operation. The implementation introduces the following concepts to the error
+handler:
+
+ -failure speed:
+ Defines how fast XFS should propagate an error upwards when a specific
+ error is found during the filesystem operation. It can propagate
+ immediately, after a defined number of retries, after a set time period,
+ or simply retry forever.
+
+ -error classes:
+ Specifies the subsystem the error configuration will apply to, such as
+ metadata IO or memory allocation. Different subsystems will have
+ different error handlers for which behaviour can be configured.
+
+ -error handlers:
+ Defines the behavior for a specific error.
+
+The filesystem behavior during an error can be set via ``sysfs`` files. Each
+error handler works independently - the first condition met by an error handler
+for a specific class will cause the error to be propagated rather than reset and
+retried.
+
+The action taken by the filesystem when the error is propagated is context
+dependent - it may cause a shut down in the case of an unrecoverable error,
+it may be reported back to userspace, or it may even be ignored because
+there's nothing useful we can with the error or anyone we can report it to (e.g.
+during unmount).
+
+The configuration files are organized into the following hierarchy for each
+mounted filesystem:
+
+ /sys/fs/xfs/<dev>/error/<class>/<error>/
+
+Where:
+ <dev>
+ The short device name of the mounted filesystem. This is the same device
+ name that shows up in XFS kernel error messages as "XFS(<dev>): ..."
+
+ <class>
+ The subsystem the error configuration belongs to. As of 4.9, the defined
+ classes are:
+
+ - "metadata": applies metadata buffer write IO
+
+ <error>
+ The individual error handler configurations.
+
+
+Each filesystem has "global" error configuration options defined in their top
+level directory:
+
+ /sys/fs/xfs/<dev>/error/
+
+ fail_at_unmount (Min: 0 Default: 1 Max: 1)
+ Defines the filesystem error behavior at unmount time.
+
+ If set to a value of 1, XFS will override all other error configurations
+ during unmount and replace them with "immediate fail" characteristics.
+ i.e. no retries, no retry timeout. This will always allow unmount to
+ succeed when there are persistent errors present.
+
+ If set to 0, the configured retry behaviour will continue until all
+ retries and/or timeouts have been exhausted. This will delay unmount
+ completion when there are persistent errors, and it may prevent the
+ filesystem from ever unmounting fully in the case of "retry forever"
+ handler configurations.
+
+ Note: there is no guarantee that fail_at_unmount can be set while an
+ unmount is in progress. It is possible that the ``sysfs`` entries are
+ removed by the unmounting filesystem before a "retry forever" error
+ handler configuration causes unmount to hang, and hence the filesystem
+ must be configured appropriately before unmount begins to prevent
+ unmount hangs.
+
+Each filesystem has specific error class handlers that define the error
+propagation behaviour for specific errors. There is also a "default" error
+handler defined, which defines the behaviour for all errors that don't have
+specific handlers defined. Where multiple retry constraints are configured for
+a single error, the first retry configuration that expires will cause the error
+to be propagated. The handler configurations are found in the directory:
+
+ /sys/fs/xfs/<dev>/error/<class>/<error>/
+
+ max_retries (Min: -1 Default: Varies Max: INTMAX)
+ Defines the allowed number of retries of a specific error before
+ the filesystem will propagate the error. The retry count for a given
+ error context (e.g. a specific metadata buffer) is reset every time
+ there is a successful completion of the operation.
+
+ Setting the value to "-1" will cause XFS to retry forever for this
+ specific error.
+
+ Setting the value to "0" will cause XFS to fail immediately when the
+ specific error is reported.
+
+ Setting the value to "N" (where 0 < N < Max) will make XFS retry the
+ operation "N" times before propagating the error.
+
+ retry_timeout_seconds (Min: -1 Default: Varies Max: 1 day)
+ Define the amount of time (in seconds) that the filesystem is
+ allowed to retry its operations when the specific error is
+ found.
+
+ Setting the value to "-1" will allow XFS to retry forever for this
+ specific error.
+
+ Setting the value to "0" will cause XFS to fail immediately when the
+ specific error is reported.
+
+ Setting the value to "N" (where 0 < N < Max) will allow XFS to retry the
+ operation for up to "N" seconds before propagating the error.
+
+**Note:** The default behaviour for a specific error handler is dependent on both
+the class and error context. For example, the default values for
+"metadata/ENODEV" are "0" rather than "-1" so that this error handler defaults
+to "fail immediately" behaviour. This is done because ENODEV is a fatal,
+unrecoverable error no matter how many times the metadata IO is retried.
+++ /dev/null
-
-The SGI XFS Filesystem
-======================
-
-XFS is a high performance journaling filesystem which originated
-on the SGI IRIX platform. It is completely multi-threaded, can
-support large files and large filesystems, extended attributes,
-variable block sizes, is extent based, and makes extensive use of
-Btrees (directories, extents, free space) to aid both performance
-and scalability.
-
-Refer to the documentation at https://xfs.wiki.kernel.org/
-for further details. This implementation is on-disk compatible
-with the IRIX version of XFS.
-
-
-Mount Options
-=============
-
-When mounting an XFS filesystem, the following options are accepted.
-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.
-
- 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.
-
- 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. 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.
- An XFS filesystem has up to three parts: a data section, a log
- section, and a real-time section. The real-time section is
- optional, and the log section can be separate from the data
- section or contained within it.
-
- noalign
- 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.
- If the filesystem was not cleanly unmounted, it is likely to
- be inconsistent when mounted in "norecovery" mode.
- Some files or directories may not be accessible because of this.
- Filesystems mounted "norecovery" must be mounted read-only or
- 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,
- and often used in combination with "norecovery" for mounting
- read-only snapshots.
-
- 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. Refer to xfs_quota(8) for further details.
-
- gquota/grpquota/gqnoenforce
- Group disk quota accounting enabled and limits (optionally)
- 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. 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
-========================
-
- Name Removal Schedule
- ---- ----------------
-
-
-Removed Mount Options
-=====================
-
- Name Removed
- ---- -------
- delaylog/nodelaylog v4.0
- ihashsize v4.0
- irixsgid v4.0
- osyncisdsync/osyncisosync v4.0
- barrier v4.19
- nobarrier v4.19
-
-
-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
- 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 filesystem flushes metadata
- out to disk and runs internal cache cleanup routines.
-
- 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.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.
- This will generate detailed messages & backtraces for filesystem
- shutdowns, for example. Current threshold values are:
-
- XFS_ERRLEVEL_OFF: 0
- XFS_ERRLEVEL_LOW: 1
- XFS_ERRLEVEL_HIGH: 5
-
- fs.xfs.panic_mask (Min: 0 Default: 0 Max: 256)
- Causes certain error conditions to call BUG(). Value is a bitmask;
- OR together the tags which represent errors which should cause panics:
-
- XFS_NO_PTAG 0
- XFS_PTAG_IFLUSH 0x00000001
- XFS_PTAG_LOGRES 0x00000002
- XFS_PTAG_AILDELETE 0x00000004
- XFS_PTAG_ERROR_REPORT 0x00000008
- XFS_PTAG_SHUTDOWN_CORRUPT 0x00000010
- XFS_PTAG_SHUTDOWN_IOERROR 0x00000020
- XFS_PTAG_SHUTDOWN_LOGERROR 0x00000040
- XFS_PTAG_FSBLOCK_ZERO 0x00000080
- XFS_PTAG_VERIFIER_ERROR 0x00000100
-
- 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)
- or whether their mode is affected by the umask (irix mode).
-
- 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
- is set.
-
- 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_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_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_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
-==================
-
-None at present.
-
-
-Removed Sysctls
-===============
-
- Name Removed
- ---- -------
- fs.xfs.xfsbufd_centisec v4.0
- fs.xfs.age_buffer_centisecs v4.0
-
-
-Error handling
-==============
-
-XFS can act differently according to the type of error found during its
-operation. The implementation introduces the following concepts to the error
-handler:
-
- -failure speed:
- Defines how fast XFS should propagate an error upwards when a specific
- error is found during the filesystem operation. It can propagate
- immediately, after a defined number of retries, after a set time period,
- or simply retry forever.
-
- -error classes:
- Specifies the subsystem the error configuration will apply to, such as
- metadata IO or memory allocation. Different subsystems will have
- different error handlers for which behaviour can be configured.
-
- -error handlers:
- Defines the behavior for a specific error.
-
-The filesystem behavior during an error can be set via sysfs files. Each
-error handler works independently - the first condition met by an error handler
-for a specific class will cause the error to be propagated rather than reset and
-retried.
-
-The action taken by the filesystem when the error is propagated is context
-dependent - it may cause a shut down in the case of an unrecoverable error,
-it may be reported back to userspace, or it may even be ignored because
-there's nothing useful we can with the error or anyone we can report it to (e.g.
-during unmount).
-
-The configuration files are organized into the following hierarchy for each
-mounted filesystem:
-
- /sys/fs/xfs/<dev>/error/<class>/<error>/
-
-Where:
- <dev>
- The short device name of the mounted filesystem. This is the same device
- name that shows up in XFS kernel error messages as "XFS(<dev>): ..."
-
- <class>
- The subsystem the error configuration belongs to. As of 4.9, the defined
- classes are:
-
- - "metadata": applies metadata buffer write IO
-
- <error>
- The individual error handler configurations.
-
-
-Each filesystem has "global" error configuration options defined in their top
-level directory:
-
- /sys/fs/xfs/<dev>/error/
-
- fail_at_unmount (Min: 0 Default: 1 Max: 1)
- Defines the filesystem error behavior at unmount time.
-
- If set to a value of 1, XFS will override all other error configurations
- during unmount and replace them with "immediate fail" characteristics.
- i.e. no retries, no retry timeout. This will always allow unmount to
- succeed when there are persistent errors present.
-
- If set to 0, the configured retry behaviour will continue until all
- retries and/or timeouts have been exhausted. This will delay unmount
- completion when there are persistent errors, and it may prevent the
- filesystem from ever unmounting fully in the case of "retry forever"
- handler configurations.
-
- Note: there is no guarantee that fail_at_unmount can be set while an
- unmount is in progress. It is possible that the sysfs entries are
- removed by the unmounting filesystem before a "retry forever" error
- handler configuration causes unmount to hang, and hence the filesystem
- must be configured appropriately before unmount begins to prevent
- unmount hangs.
-
-Each filesystem has specific error class handlers that define the error
-propagation behaviour for specific errors. There is also a "default" error
-handler defined, which defines the behaviour for all errors that don't have
-specific handlers defined. Where multiple retry constraints are configuredi for
-a single error, the first retry configuration that expires will cause the error
-to be propagated. The handler configurations are found in the directory:
-
- /sys/fs/xfs/<dev>/error/<class>/<error>/
-
- max_retries (Min: -1 Default: Varies Max: INTMAX)
- Defines the allowed number of retries of a specific error before
- the filesystem will propagate the error. The retry count for a given
- error context (e.g. a specific metadata buffer) is reset every time
- there is a successful completion of the operation.
-
- Setting the value to "-1" will cause XFS to retry forever for this
- specific error.
-
- Setting the value to "0" will cause XFS to fail immediately when the
- specific error is reported.
-
- Setting the value to "N" (where 0 < N < Max) will make XFS retry the
- operation "N" times before propagating the error.
-
- retry_timeout_seconds (Min: -1 Default: Varies Max: 1 day)
- Define the amount of time (in seconds) that the filesystem is
- allowed to retry its operations when the specific error is
- found.
-
- Setting the value to "-1" will allow XFS to retry forever for this
- specific error.
-
- Setting the value to "0" will cause XFS to fail immediately when the
- specific error is reported.
-
- Setting the value to "N" (where 0 < N < Max) will allow XFS to retry the
- operation for up to "N" seconds before propagating the error.
-
-Note: The default behaviour for a specific error handler is dependent on both
-the class and error context. For example, the default values for
-"metadata/ENODEV" are "0" rather than "-1" so that this error handler defaults
-to "fail immediately" behaviour. This is done because ENODEV is a fatal,
-unrecoverable error no matter how many times the metadata IO is retried.
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