5 XFS is a high performance journaling filesystem which originated
6 on the SGI IRIX platform. It is completely multi-threaded, can
7 support large files and large filesystems, extended attributes,
8 variable block sizes, is extent based, and makes extensive use of
9 Btrees (directories, extents, free space) to aid both performance
12 Refer to the documentation at https://xfs.wiki.kernel.org/
13 for further details. This implementation is on-disk compatible
14 with the IRIX version of XFS.
20 When mounting an XFS filesystem, the following options are accepted.
21 For boolean mount options, the names with the (*) suffix is the
25 Sets the buffered I/O end-of-file preallocation size when
26 doing delayed allocation writeout (default size is 64KiB).
27 Valid values for this option are page size (typically 4KiB)
28 through to 1GiB, inclusive, in power-of-2 increments.
30 The default behaviour is for dynamic end-of-file
31 preallocation size, which uses a set of heuristics to
32 optimise the preallocation size based on the current
33 allocation patterns within the file and the access patterns
34 to the file. Specifying a fixed allocsize value turns off
35 the dynamic behaviour.
39 The options enable/disable an "opportunistic" improvement to
40 be made in the way inline extended attributes are stored
41 on-disk. When the new form is used for the first time when
42 attr2 is selected (either when setting or removing extended
43 attributes) the on-disk superblock feature bit field will be
44 updated to reflect this format being in use.
46 The default behaviour is determined by the on-disk feature
47 bit indicating that attr2 behaviour is active. If either
48 mount option it set, then that becomes the new default used
51 CRC enabled filesystems always use the attr2 format, and so
52 will reject the noattr2 mount option if it is set.
56 Enable/disable the issuing of commands to let the block
57 device reclaim space freed by the filesystem. This is
58 useful for SSD devices, thinly provisioned LUNs and virtual
59 machine images, but may have a performance impact.
61 Note: It is currently recommended that you use the fstrim
62 application to discard unused blocks rather than the discard
63 mount option because the performance impact of this option
67 nogrpid/sysvgroups (*)
68 These options define what group ID a newly created file
69 gets. When grpid is set, it takes the group ID of the
70 directory in which it is created; otherwise it takes the
71 fsgid of the current process, unless the directory has the
72 setgid bit set, in which case it takes the gid from the
73 parent directory, and also gets the setgid bit set if it is
77 Make the data allocator use the filestreams allocation mode
78 across the entire filesystem rather than just on directories
83 When ikeep is specified, XFS does not delete empty inode
84 clusters and keeps them around on disk. When noikeep is
85 specified, empty inode clusters are returned to the free
90 When inode32 is specified, it indicates that XFS limits
91 inode creation to locations which will not result in inode
92 numbers with more than 32 bits of significance.
94 When inode64 is specified, it indicates that XFS is allowed
95 to create inodes at any location in the filesystem,
96 including those which will result in inode numbers occupying
97 more than 32 bits of significance.
99 inode32 is provided for backwards compatibility with older
100 systems and applications, since 64 bits inode numbers might
101 cause problems for some applications that cannot handle
102 large inode numbers. If applications are in use which do
103 not handle inode numbers bigger than 32 bits, the inode32
104 option should be specified.
109 If "nolargeio" is specified, the optimal I/O reported in
110 st_blksize by stat(2) will be as small as possible to allow
111 user applications to avoid inefficient read/modify/write
112 I/O. This is typically the page size of the machine, as
113 this is the granularity of the page cache.
115 If "largeio" specified, a filesystem that was created with a
116 "swidth" specified will return the "swidth" value (in bytes)
117 in st_blksize. If the filesystem does not have a "swidth"
118 specified but does specify an "allocsize" then "allocsize"
119 (in bytes) will be returned instead. Otherwise the behaviour
120 is the same as if "nolargeio" was specified.
123 Set the number of in-memory log buffers. Valid numbers
124 range from 2-8 inclusive.
126 The default value is 8 buffers.
128 If the memory cost of 8 log buffers is too high on small
129 systems, then it may be reduced at some cost to performance
130 on metadata intensive workloads. The logbsize option below
131 controls the size of each buffer and so is also relevant to
135 Set the size of each in-memory log buffer. The size may be
136 specified in bytes, or in kilobytes with a "k" suffix.
137 Valid sizes for version 1 and version 2 logs are 16384 (16k)
138 and 32768 (32k). Valid sizes for version 2 logs also
139 include 65536 (64k), 131072 (128k) and 262144 (256k). The
140 logbsize must be an integer multiple of the log
141 stripe unit configured at mkfs time.
143 The default value for for version 1 logs is 32768, while the
144 default value for version 2 logs is MAX(32768, log_sunit).
146 logdev=device and rtdev=device
147 Use an external log (metadata journal) and/or real-time device.
148 An XFS filesystem has up to three parts: a data section, a log
149 section, and a real-time section. The real-time section is
150 optional, and the log section can be separate from the data
151 section or contained within it.
154 Data allocations will not be aligned at stripe unit
155 boundaries. This is only relevant to filesystems created
156 with non-zero data alignment parameters (sunit, swidth) by
160 The filesystem will be mounted without running log recovery.
161 If the filesystem was not cleanly unmounted, it is likely to
162 be inconsistent when mounted in "norecovery" mode.
163 Some files or directories may not be accessible because of this.
164 Filesystems mounted "norecovery" must be mounted read-only or
168 Don't check for double mounted file systems using the file
169 system uuid. This is useful to mount LVM snapshot volumes,
170 and often used in combination with "norecovery" for mounting
174 Forcibly turns off all quota accounting and enforcement
175 within the filesystem.
177 uquota/usrquota/uqnoenforce/quota
178 User disk quota accounting enabled, and limits (optionally)
179 enforced. Refer to xfs_quota(8) for further details.
181 gquota/grpquota/gqnoenforce
182 Group disk quota accounting enabled and limits (optionally)
183 enforced. Refer to xfs_quota(8) for further details.
185 pquota/prjquota/pqnoenforce
186 Project disk quota accounting enabled and limits (optionally)
187 enforced. Refer to xfs_quota(8) for further details.
189 sunit=value and swidth=value
190 Used to specify the stripe unit and width for a RAID device
191 or a stripe volume. "value" must be specified in 512-byte
192 block units. These options are only relevant to filesystems
193 that were created with non-zero data alignment parameters.
195 The sunit and swidth parameters specified must be compatible
196 with the existing filesystem alignment characteristics. In
197 general, that means the only valid changes to sunit are
198 increasing it by a power-of-2 multiple. Valid swidth values
199 are any integer multiple of a valid sunit value.
201 Typically the only time these mount options are necessary if
202 after an underlying RAID device has had it's geometry
203 modified, such as adding a new disk to a RAID5 lun and
207 Data allocations will be rounded up to stripe width boundaries
208 when the current end of file is being extended and the file
209 size is larger than the stripe width size.
212 When specified, all filesystem namespace operations are
213 executed synchronously. This ensures that when the namespace
214 operation (create, unlink, etc) completes, the change to the
215 namespace is on stable storage. This is useful in HA setups
216 where failover must not result in clients seeing
217 inconsistent namespace presentation during or after a
221 Deprecated Mount Options
222 ========================
224 Name Removal Schedule
225 ---- ----------------
226 barrier no earlier than v4.15
227 nobarrier no earlier than v4.15
230 Removed Mount Options
231 =====================
235 delaylog/nodelaylog v4.0
238 osyncisdsync/osyncisosync v4.0
244 The following sysctls are available for the XFS filesystem:
246 fs.xfs.stats_clear (Min: 0 Default: 0 Max: 1)
247 Setting this to "1" clears accumulated XFS statistics
248 in /proc/fs/xfs/stat. It then immediately resets to "0".
250 fs.xfs.xfssyncd_centisecs (Min: 100 Default: 3000 Max: 720000)
251 The interval at which the filesystem flushes metadata
252 out to disk and runs internal cache cleanup routines.
254 fs.xfs.filestream_centisecs (Min: 1 Default: 3000 Max: 360000)
255 The interval at which the filesystem ages filestreams cache
256 references and returns timed-out AGs back to the free stream
259 fs.xfs.speculative_prealloc_lifetime
260 (Units: seconds Min: 1 Default: 300 Max: 86400)
261 The interval at which the background scanning for inodes
262 with unused speculative preallocation runs. The scan
263 removes unused preallocation from clean inodes and releases
264 the unused space back to the free pool.
266 fs.xfs.error_level (Min: 0 Default: 3 Max: 11)
267 A volume knob for error reporting when internal errors occur.
268 This will generate detailed messages & backtraces for filesystem
269 shutdowns, for example. Current threshold values are:
275 fs.xfs.panic_mask (Min: 0 Default: 0 Max: 255)
276 Causes certain error conditions to call BUG(). Value is a bitmask;
277 OR together the tags which represent errors which should cause panics:
280 XFS_PTAG_IFLUSH 0x00000001
281 XFS_PTAG_LOGRES 0x00000002
282 XFS_PTAG_AILDELETE 0x00000004
283 XFS_PTAG_ERROR_REPORT 0x00000008
284 XFS_PTAG_SHUTDOWN_CORRUPT 0x00000010
285 XFS_PTAG_SHUTDOWN_IOERROR 0x00000020
286 XFS_PTAG_SHUTDOWN_LOGERROR 0x00000040
287 XFS_PTAG_FSBLOCK_ZERO 0x00000080
289 This option is intended for debugging only.
291 fs.xfs.irix_symlink_mode (Min: 0 Default: 0 Max: 1)
292 Controls whether symlinks are created with mode 0777 (default)
293 or whether their mode is affected by the umask (irix mode).
295 fs.xfs.irix_sgid_inherit (Min: 0 Default: 0 Max: 1)
296 Controls files created in SGID directories.
297 If the group ID of the new file does not match the effective group
298 ID or one of the supplementary group IDs of the parent dir, the
299 ISGID bit is cleared if the irix_sgid_inherit compatibility sysctl
302 fs.xfs.inherit_sync (Min: 0 Default: 1 Max: 1)
303 Setting this to "1" will cause the "sync" flag set
304 by the xfs_io(8) chattr command on a directory to be
305 inherited by files in that directory.
307 fs.xfs.inherit_nodump (Min: 0 Default: 1 Max: 1)
308 Setting this to "1" will cause the "nodump" flag set
309 by the xfs_io(8) chattr command on a directory to be
310 inherited by files in that directory.
312 fs.xfs.inherit_noatime (Min: 0 Default: 1 Max: 1)
313 Setting this to "1" will cause the "noatime" flag set
314 by the xfs_io(8) chattr command on a directory to be
315 inherited by files in that directory.
317 fs.xfs.inherit_nosymlinks (Min: 0 Default: 1 Max: 1)
318 Setting this to "1" will cause the "nosymlinks" flag set
319 by the xfs_io(8) chattr command on a directory to be
320 inherited by files in that directory.
322 fs.xfs.inherit_nodefrag (Min: 0 Default: 1 Max: 1)
323 Setting this to "1" will cause the "nodefrag" flag set
324 by the xfs_io(8) chattr command on a directory to be
325 inherited by files in that directory.
327 fs.xfs.rotorstep (Min: 1 Default: 1 Max: 256)
328 In "inode32" allocation mode, this option determines how many
329 files the allocator attempts to allocate in the same allocation
330 group before moving to the next allocation group. The intent
331 is to control the rate at which the allocator moves between
332 allocation groups when allocating extents for new files.
345 fs.xfs.xfsbufd_centisec v4.0
346 fs.xfs.age_buffer_centisecs v4.0
352 XFS can act differently according to the type of error found during its
353 operation. The implementation introduces the following concepts to the error
357 Defines how fast XFS should propagate an error upwards when a specific
358 error is found during the filesystem operation. It can propagate
359 immediately, after a defined number of retries, after a set time period,
360 or simply retry forever.
363 Specifies the subsystem the error configuration will apply to, such as
364 metadata IO or memory allocation. Different subsystems will have
365 different error handlers for which behaviour can be configured.
368 Defines the behavior for a specific error.
370 The filesystem behavior during an error can be set via sysfs files. Each
371 error handler works independently - the first condition met by an error handler
372 for a specific class will cause the error to be propagated rather than reset and
375 The action taken by the filesystem when the error is propagated is context
376 dependent - it may cause a shut down in the case of an unrecoverable error,
377 it may be reported back to userspace, or it may even be ignored because
378 there's nothing useful we can with the error or anyone we can report it to (e.g.
381 The configuration files are organized into the following hierarchy for each
384 /sys/fs/xfs/<dev>/error/<class>/<error>/
388 The short device name of the mounted filesystem. This is the same device
389 name that shows up in XFS kernel error messages as "XFS(<dev>): ..."
392 The subsystem the error configuration belongs to. As of 4.9, the defined
395 - "metadata": applies metadata buffer write IO
398 The individual error handler configurations.
401 Each filesystem has "global" error configuration options defined in their top
404 /sys/fs/xfs/<dev>/error/
406 fail_at_unmount (Min: 0 Default: 1 Max: 1)
407 Defines the filesystem error behavior at unmount time.
409 If set to a value of 1, XFS will override all other error configurations
410 during unmount and replace them with "immediate fail" characteristics.
411 i.e. no retries, no retry timeout. This will always allow unmount to
412 succeed when there are persistent errors present.
414 If set to 0, the configured retry behaviour will continue until all
415 retries and/or timeouts have been exhausted. This will delay unmount
416 completion when there are persistent errors, and it may prevent the
417 filesystem from ever unmounting fully in the case of "retry forever"
418 handler configurations.
420 Note: there is no guarantee that fail_at_unmount can be set whilst an
421 unmount is in progress. It is possible that the sysfs entries are
422 removed by the unmounting filesystem before a "retry forever" error
423 handler configuration causes unmount to hang, and hence the filesystem
424 must be configured appropriately before unmount begins to prevent
427 Each filesystem has specific error class handlers that define the error
428 propagation behaviour for specific errors. There is also a "default" error
429 handler defined, which defines the behaviour for all errors that don't have
430 specific handlers defined. Where multiple retry constraints are configuredi for
431 a single error, the first retry configuration that expires will cause the error
432 to be propagated. The handler configurations are found in the directory:
434 /sys/fs/xfs/<dev>/error/<class>/<error>/
436 max_retries (Min: -1 Default: Varies Max: INTMAX)
437 Defines the allowed number of retries of a specific error before
438 the filesystem will propagate the error. The retry count for a given
439 error context (e.g. a specific metadata buffer) is reset every time
440 there is a successful completion of the operation.
442 Setting the value to "-1" will cause XFS to retry forever for this
445 Setting the value to "0" will cause XFS to fail immediately when the
446 specific error is reported.
448 Setting the value to "N" (where 0 < N < Max) will make XFS retry the
449 operation "N" times before propagating the error.
451 retry_timeout_seconds (Min: -1 Default: Varies Max: 1 day)
452 Define the amount of time (in seconds) that the filesystem is
453 allowed to retry its operations when the specific error is
456 Setting the value to "-1" will allow XFS to retry forever for this
459 Setting the value to "0" will cause XFS to fail immediately when the
460 specific error is reported.
462 Setting the value to "N" (where 0 < N < Max) will allow XFS to retry the
463 operation for up to "N" seconds before propagating the error.
465 Note: The default behaviour for a specific error handler is dependent on both
466 the class and error context. For example, the default values for
467 "metadata/ENODEV" are "0" rather than "-1" so that this error handler defaults
468 to "fail immediately" behaviour. This is done because ENODEV is a fatal,
469 unrecoverable error no matter how many times the metadata IO is retried.