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 http://oss.sgi.com/projects/xfs/
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.
23 Sets the buffered I/O end-of-file preallocation size when
24 doing delayed allocation writeout (default size is 64KiB).
25 Valid values for this option are page size (typically 4KiB)
26 through to 1GiB, inclusive, in power-of-2 increments.
29 The options enable/disable (default is disabled for backward
30 compatibility on-disk) an "opportunistic" improvement to be
31 made in the way inline extended attributes are stored on-disk.
32 When the new form is used for the first time (by setting or
33 removing extended attributes) the on-disk superblock feature
34 bit field will be updated to reflect this format being in use.
37 Enables the use of block layer write barriers for writes into
38 the journal and unwritten extent conversion. This allows for
39 drive level write caching to be enabled, for devices that
40 support write barriers.
43 Enable the DMAPI (Data Management API) event callouts.
44 Use with the "mtpt" option.
46 grpid/bsdgroups and nogrpid/sysvgroups
47 These options define what group ID a newly created file gets.
48 When grpid is set, it takes the group ID of the directory in
49 which it is created; otherwise (the default) it takes the fsgid
50 of the current process, unless the directory has the setgid bit
51 set, in which case it takes the gid from the parent directory,
52 and also gets the setgid bit set if it is a directory itself.
55 In memory inode hashes have been removed, so this option has
56 no function as of August 2007. Option is deprecated.
59 When ikeep is specified, XFS does not delete empty inode clusters
60 and keeps them around on disk. ikeep is the traditional XFS
61 behaviour. When noikeep is specified, empty inode clusters
62 are returned to the free space pool. The default is noikeep for
63 non-DMAPI mounts, while ikeep is the default when DMAPI is in use.
66 Indicates that XFS is allowed to create inodes at any location
67 in the filesystem, including those which will result in inode
68 numbers occupying more than 32 bits of significance. This is
69 provided for backwards compatibility, but causes problems for
70 backup applications that cannot handle large inode numbers.
73 If "nolargeio" is specified, the optimal I/O reported in
74 st_blksize by stat(2) will be as small as possible to allow user
75 applications to avoid inefficient read/modify/write I/O.
76 If "largeio" specified, a filesystem that has a "swidth" specified
77 will return the "swidth" value (in bytes) in st_blksize. If the
78 filesystem does not have a "swidth" specified but does specify
79 an "allocsize" then "allocsize" (in bytes) will be returned
81 If neither of these two options are specified, then filesystem
82 will behave as if "nolargeio" was specified.
85 Set the number of in-memory log buffers. Valid numbers range
87 The default value is 8 buffers for filesystems with a
88 blocksize of 64KiB, 4 buffers for filesystems with a blocksize
89 of 32KiB, 3 buffers for filesystems with a blocksize of 16KiB
90 and 2 buffers for all other configurations. Increasing the
91 number of buffers may increase performance on some workloads
92 at the cost of the memory used for the additional log buffers
93 and their associated control structures.
96 Set the size of each in-memory log buffer.
97 Size may be specified in bytes, or in kilobytes with a "k" suffix.
98 Valid sizes for version 1 and version 2 logs are 16384 (16k) and
99 32768 (32k). Valid sizes for version 2 logs also include
100 65536 (64k), 131072 (128k) and 262144 (256k).
101 The default value for machines with more than 32MiB of memory
102 is 32768, machines with less memory use 16384 by default.
104 logdev=device and rtdev=device
105 Use an external log (metadata journal) and/or real-time device.
106 An XFS filesystem has up to three parts: a data section, a log
107 section, and a real-time section. The real-time section is
108 optional, and the log section can be separate from the data
109 section or contained within it.
112 Use with the "dmapi" option. The value specified here will be
113 included in the DMAPI mount event, and should be the path of
114 the actual mountpoint that is used.
117 Data allocations will not be aligned at stripe unit boundaries.
120 Access timestamps are not updated when a file is read.
123 The filesystem will be mounted without running log recovery.
124 If the filesystem was not cleanly unmounted, it is likely to
125 be inconsistent when mounted in "norecovery" mode.
126 Some files or directories may not be accessible because of this.
127 Filesystems mounted "norecovery" must be mounted read-only or
131 Don't check for double mounted file systems using the file system uuid.
132 This is useful to mount LVM snapshot volumes.
135 Make O_SYNC writes implement true O_SYNC. WITHOUT this option,
136 Linux XFS behaves as if an "osyncisdsync" option is used,
137 which will make writes to files opened with the O_SYNC flag set
138 behave as if the O_DSYNC flag had been used instead.
139 This can result in better performance without compromising
141 However if this option is not in effect, timestamp updates from
142 O_SYNC writes can be lost if the system crashes.
143 If timestamp updates are critical, use the osyncisosync option.
145 uquota/usrquota/uqnoenforce/quota
146 User disk quota accounting enabled, and limits (optionally)
147 enforced. Refer to xfs_quota(8) for further details.
149 gquota/grpquota/gqnoenforce
150 Group disk quota accounting enabled and limits (optionally)
151 enforced. Refer to xfs_quota(8) for further details.
153 pquota/prjquota/pqnoenforce
154 Project disk quota accounting enabled and limits (optionally)
155 enforced. Refer to xfs_quota(8) for further details.
157 sunit=value and swidth=value
158 Used to specify the stripe unit and width for a RAID device or
159 a stripe volume. "value" must be specified in 512-byte block
161 If this option is not specified and the filesystem was made on
162 a stripe volume or the stripe width or unit were specified for
163 the RAID device at mkfs time, then the mount system call will
164 restore the value from the superblock. For filesystems that
165 are made directly on RAID devices, these options can be used
166 to override the information in the superblock if the underlying
167 disk layout changes after the filesystem has been created.
168 The "swidth" option is required if the "sunit" option has been
169 specified, and must be a multiple of the "sunit" value.
172 Data allocations will be rounded up to stripe width boundaries
173 when the current end of file is being extended and the file
174 size is larger than the stripe width size.
180 The following sysctls are available for the XFS filesystem:
182 fs.xfs.stats_clear (Min: 0 Default: 0 Max: 1)
183 Setting this to "1" clears accumulated XFS statistics
184 in /proc/fs/xfs/stat. It then immediately resets to "0".
186 fs.xfs.xfssyncd_centisecs (Min: 100 Default: 3000 Max: 720000)
187 The interval at which the xfssyncd thread flushes metadata
188 out to disk. This thread will flush log activity out, and
189 do some processing on unlinked inodes.
191 fs.xfs.xfsbufd_centisecs (Min: 50 Default: 100 Max: 3000)
192 The interval at which xfsbufd scans the dirty metadata buffers list.
194 fs.xfs.age_buffer_centisecs (Min: 100 Default: 1500 Max: 720000)
195 The age at which xfsbufd flushes dirty metadata buffers to disk.
197 fs.xfs.error_level (Min: 0 Default: 3 Max: 11)
198 A volume knob for error reporting when internal errors occur.
199 This will generate detailed messages & backtraces for filesystem
200 shutdowns, for example. Current threshold values are:
206 fs.xfs.panic_mask (Min: 0 Default: 0 Max: 127)
207 Causes certain error conditions to call BUG(). Value is a bitmask;
208 AND together the tags which represent errors which should cause panics:
211 XFS_PTAG_IFLUSH 0x00000001
212 XFS_PTAG_LOGRES 0x00000002
213 XFS_PTAG_AILDELETE 0x00000004
214 XFS_PTAG_ERROR_REPORT 0x00000008
215 XFS_PTAG_SHUTDOWN_CORRUPT 0x00000010
216 XFS_PTAG_SHUTDOWN_IOERROR 0x00000020
217 XFS_PTAG_SHUTDOWN_LOGERROR 0x00000040
219 This option is intended for debugging only.
221 fs.xfs.irix_symlink_mode (Min: 0 Default: 0 Max: 1)
222 Controls whether symlinks are created with mode 0777 (default)
223 or whether their mode is affected by the umask (irix mode).
225 fs.xfs.irix_sgid_inherit (Min: 0 Default: 0 Max: 1)
226 Controls files created in SGID directories.
227 If the group ID of the new file does not match the effective group
228 ID or one of the supplementary group IDs of the parent dir, the
229 ISGID bit is cleared if the irix_sgid_inherit compatibility sysctl
232 fs.xfs.inherit_sync (Min: 0 Default: 1 Max: 1)
233 Setting this to "1" will cause the "sync" flag set
234 by the xfs_io(8) chattr command on a directory to be
235 inherited by files in that directory.
237 fs.xfs.inherit_nodump (Min: 0 Default: 1 Max: 1)
238 Setting this to "1" will cause the "nodump" flag set
239 by the xfs_io(8) chattr command on a directory to be
240 inherited by files in that directory.
242 fs.xfs.inherit_noatime (Min: 0 Default: 1 Max: 1)
243 Setting this to "1" will cause the "noatime" flag set
244 by the xfs_io(8) chattr command on a directory to be
245 inherited by files in that directory.
247 fs.xfs.inherit_nosymlinks (Min: 0 Default: 1 Max: 1)
248 Setting this to "1" will cause the "nosymlinks" flag set
249 by the xfs_io(8) chattr command on a directory to be
250 inherited by files in that directory.
252 fs.xfs.rotorstep (Min: 1 Default: 1 Max: 256)
253 In "inode32" allocation mode, this option determines how many
254 files the allocator attempts to allocate in the same allocation
255 group before moving to the next allocation group. The intent
256 is to control the rate at which the allocator moves between
257 allocation groups when allocating extents for new files.