Loading...
Note: File does not exist in v6.8.
1
2The SGI XFS Filesystem
3======================
4
5XFS is a high performance journaling filesystem which originated
6on the SGI IRIX platform. It is completely multi-threaded, can
7support large files and large filesystems, extended attributes,
8variable block sizes, is extent based, and makes extensive use of
9Btrees (directories, extents, free space) to aid both performance
10and scalability.
11
12Refer to the documentation at http://oss.sgi.com/projects/xfs/
13for further details. This implementation is on-disk compatible
14with the IRIX version of XFS.
15
16
17Mount Options
18=============
19
20When mounting an XFS filesystem, the following options are accepted.
21
22 allocsize=size
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.
27
28 attr2/noattr2
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.
35
36 barrier
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.
41
42 discard
43 Issue command to let the block device reclaim space freed by the
44 filesystem. This is useful for SSD devices, thinly provisioned
45 LUNs and virtual machine images, but may have a performance
46 impact. This option is incompatible with the nodelaylog option.
47
48 dmapi
49 Enable the DMAPI (Data Management API) event callouts.
50 Use with the "mtpt" option.
51
52 grpid/bsdgroups and nogrpid/sysvgroups
53 These options define what group ID a newly created file gets.
54 When grpid is set, it takes the group ID of the directory in
55 which it is created; otherwise (the default) it takes the fsgid
56 of the current process, unless the directory has the setgid bit
57 set, in which case it takes the gid from the parent directory,
58 and also gets the setgid bit set if it is a directory itself.
59
60 ihashsize=value
61 In memory inode hashes have been removed, so this option has
62 no function as of August 2007. Option is deprecated.
63
64 ikeep/noikeep
65 When ikeep is specified, XFS does not delete empty inode clusters
66 and keeps them around on disk. ikeep is the traditional XFS
67 behaviour. When noikeep is specified, empty inode clusters
68 are returned to the free space pool. The default is noikeep for
69 non-DMAPI mounts, while ikeep is the default when DMAPI is in use.
70
71 inode64
72 Indicates that XFS is allowed to create inodes at any location
73 in the filesystem, including those which will result in inode
74 numbers occupying more than 32 bits of significance. This is
75 provided for backwards compatibility, but causes problems for
76 backup applications that cannot handle large inode numbers.
77
78 largeio/nolargeio
79 If "nolargeio" is specified, the optimal I/O reported in
80 st_blksize by stat(2) will be as small as possible to allow user
81 applications to avoid inefficient read/modify/write I/O.
82 If "largeio" specified, a filesystem that has a "swidth" specified
83 will return the "swidth" value (in bytes) in st_blksize. If the
84 filesystem does not have a "swidth" specified but does specify
85 an "allocsize" then "allocsize" (in bytes) will be returned
86 instead.
87 If neither of these two options are specified, then filesystem
88 will behave as if "nolargeio" was specified.
89
90 logbufs=value
91 Set the number of in-memory log buffers. Valid numbers range
92 from 2-8 inclusive.
93 The default value is 8 buffers for filesystems with a
94 blocksize of 64KiB, 4 buffers for filesystems with a blocksize
95 of 32KiB, 3 buffers for filesystems with a blocksize of 16KiB
96 and 2 buffers for all other configurations. Increasing the
97 number of buffers may increase performance on some workloads
98 at the cost of the memory used for the additional log buffers
99 and their associated control structures.
100
101 logbsize=value
102 Set the size of each in-memory log buffer.
103 Size may be specified in bytes, or in kilobytes with a "k" suffix.
104 Valid sizes for version 1 and version 2 logs are 16384 (16k) and
105 32768 (32k). Valid sizes for version 2 logs also include
106 65536 (64k), 131072 (128k) and 262144 (256k).
107 The default value for machines with more than 32MiB of memory
108 is 32768, machines with less memory use 16384 by default.
109
110 logdev=device and rtdev=device
111 Use an external log (metadata journal) and/or real-time device.
112 An XFS filesystem has up to three parts: a data section, a log
113 section, and a real-time section. The real-time section is
114 optional, and the log section can be separate from the data
115 section or contained within it.
116
117 mtpt=mountpoint
118 Use with the "dmapi" option. The value specified here will be
119 included in the DMAPI mount event, and should be the path of
120 the actual mountpoint that is used.
121
122 noalign
123 Data allocations will not be aligned at stripe unit boundaries.
124
125 noatime
126 Access timestamps are not updated when a file is read.
127
128 norecovery
129 The filesystem will be mounted without running log recovery.
130 If the filesystem was not cleanly unmounted, it is likely to
131 be inconsistent when mounted in "norecovery" mode.
132 Some files or directories may not be accessible because of this.
133 Filesystems mounted "norecovery" must be mounted read-only or
134 the mount will fail.
135
136 nouuid
137 Don't check for double mounted file systems using the file system uuid.
138 This is useful to mount LVM snapshot volumes.
139
140 uquota/usrquota/uqnoenforce/quota
141 User disk quota accounting enabled, and limits (optionally)
142 enforced. Refer to xfs_quota(8) for further details.
143
144 gquota/grpquota/gqnoenforce
145 Group disk quota accounting enabled and limits (optionally)
146 enforced. Refer to xfs_quota(8) for further details.
147
148 pquota/prjquota/pqnoenforce
149 Project disk quota accounting enabled and limits (optionally)
150 enforced. Refer to xfs_quota(8) for further details.
151
152 sunit=value and swidth=value
153 Used to specify the stripe unit and width for a RAID device or
154 a stripe volume. "value" must be specified in 512-byte block
155 units.
156 If this option is not specified and the filesystem was made on
157 a stripe volume or the stripe width or unit were specified for
158 the RAID device at mkfs time, then the mount system call will
159 restore the value from the superblock. For filesystems that
160 are made directly on RAID devices, these options can be used
161 to override the information in the superblock if the underlying
162 disk layout changes after the filesystem has been created.
163 The "swidth" option is required if the "sunit" option has been
164 specified, and must be a multiple of the "sunit" value.
165
166 swalloc
167 Data allocations will be rounded up to stripe width boundaries
168 when the current end of file is being extended and the file
169 size is larger than the stripe width size.
170
171
172sysctls
173=======
174
175The following sysctls are available for the XFS filesystem:
176
177 fs.xfs.stats_clear (Min: 0 Default: 0 Max: 1)
178 Setting this to "1" clears accumulated XFS statistics
179 in /proc/fs/xfs/stat. It then immediately resets to "0".
180
181 fs.xfs.xfssyncd_centisecs (Min: 100 Default: 3000 Max: 720000)
182 The interval at which the xfssyncd thread flushes metadata
183 out to disk. This thread will flush log activity out, and
184 do some processing on unlinked inodes.
185
186 fs.xfs.xfsbufd_centisecs (Min: 50 Default: 100 Max: 3000)
187 The interval at which xfsbufd scans the dirty metadata buffers list.
188
189 fs.xfs.age_buffer_centisecs (Min: 100 Default: 1500 Max: 720000)
190 The age at which xfsbufd flushes dirty metadata buffers to disk.
191
192 fs.xfs.error_level (Min: 0 Default: 3 Max: 11)
193 A volume knob for error reporting when internal errors occur.
194 This will generate detailed messages & backtraces for filesystem
195 shutdowns, for example. Current threshold values are:
196
197 XFS_ERRLEVEL_OFF: 0
198 XFS_ERRLEVEL_LOW: 1
199 XFS_ERRLEVEL_HIGH: 5
200
201 fs.xfs.panic_mask (Min: 0 Default: 0 Max: 127)
202 Causes certain error conditions to call BUG(). Value is a bitmask;
203 AND together the tags which represent errors which should cause panics:
204
205 XFS_NO_PTAG 0
206 XFS_PTAG_IFLUSH 0x00000001
207 XFS_PTAG_LOGRES 0x00000002
208 XFS_PTAG_AILDELETE 0x00000004
209 XFS_PTAG_ERROR_REPORT 0x00000008
210 XFS_PTAG_SHUTDOWN_CORRUPT 0x00000010
211 XFS_PTAG_SHUTDOWN_IOERROR 0x00000020
212 XFS_PTAG_SHUTDOWN_LOGERROR 0x00000040
213
214 This option is intended for debugging only.
215
216 fs.xfs.irix_symlink_mode (Min: 0 Default: 0 Max: 1)
217 Controls whether symlinks are created with mode 0777 (default)
218 or whether their mode is affected by the umask (irix mode).
219
220 fs.xfs.irix_sgid_inherit (Min: 0 Default: 0 Max: 1)
221 Controls files created in SGID directories.
222 If the group ID of the new file does not match the effective group
223 ID or one of the supplementary group IDs of the parent dir, the
224 ISGID bit is cleared if the irix_sgid_inherit compatibility sysctl
225 is set.
226
227 fs.xfs.inherit_sync (Min: 0 Default: 1 Max: 1)
228 Setting this to "1" will cause the "sync" flag set
229 by the xfs_io(8) chattr command on a directory to be
230 inherited by files in that directory.
231
232 fs.xfs.inherit_nodump (Min: 0 Default: 1 Max: 1)
233 Setting this to "1" will cause the "nodump" flag set
234 by the xfs_io(8) chattr command on a directory to be
235 inherited by files in that directory.
236
237 fs.xfs.inherit_noatime (Min: 0 Default: 1 Max: 1)
238 Setting this to "1" will cause the "noatime" flag set
239 by the xfs_io(8) chattr command on a directory to be
240 inherited by files in that directory.
241
242 fs.xfs.inherit_nosymlinks (Min: 0 Default: 1 Max: 1)
243 Setting this to "1" will cause the "nosymlinks" flag set
244 by the xfs_io(8) chattr command on a directory to be
245 inherited by files in that directory.
246
247 fs.xfs.rotorstep (Min: 1 Default: 1 Max: 256)
248 In "inode32" allocation mode, this option determines how many
249 files the allocator attempts to allocate in the same allocation
250 group before moving to the next allocation group. The intent
251 is to control the rate at which the allocator moves between
252 allocation groups when allocating extents for new files.