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1da177e4 LT |
1 | |
2 | The SGI XFS Filesystem | |
3 | ====================== | |
4 | ||
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 | |
10 | and scalability. | |
11 | ||
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. | |
15 | ||
16 | ||
17 | Mount Options | |
18 | ============= | |
19 | ||
20 | When mounting an XFS filesystem, the following options are accepted. | |
21 | ||
fc97bbf3 NS |
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 | ||
f763fd44 DC |
36 | CRC enabled filesystems always use the attr2 format, and so |
37 | will reject the noattr2 mount option if it is set. | |
38 | ||
fc97bbf3 NS |
39 | barrier |
40 | Enables the use of block layer write barriers for writes into | |
41 | the journal and unwritten extent conversion. This allows for | |
42 | drive level write caching to be enabled, for devices that | |
43 | support write barriers. | |
44 | ||
e84661aa CH |
45 | discard |
46 | Issue command to let the block device reclaim space freed by the | |
47 | filesystem. This is useful for SSD devices, thinly provisioned | |
48 | LUNs and virtual machine images, but may have a performance | |
0acba3cd | 49 | impact. |
e84661aa | 50 | |
fc97bbf3 NS |
51 | dmapi |
52 | Enable the DMAPI (Data Management API) event callouts. | |
53 | Use with the "mtpt" option. | |
54 | ||
55 | grpid/bsdgroups and nogrpid/sysvgroups | |
56 | These options define what group ID a newly created file gets. | |
57 | When grpid is set, it takes the group ID of the directory in | |
58 | which it is created; otherwise (the default) it takes the fsgid | |
59 | of the current process, unless the directory has the setgid bit | |
60 | set, in which case it takes the gid from the parent directory, | |
61 | and also gets the setgid bit set if it is a directory itself. | |
62 | ||
63 | ihashsize=value | |
033bfb1a DC |
64 | In memory inode hashes have been removed, so this option has |
65 | no function as of August 2007. Option is deprecated. | |
1da177e4 LT |
66 | |
67 | ikeep/noikeep | |
033bfb1a DC |
68 | When ikeep is specified, XFS does not delete empty inode clusters |
69 | and keeps them around on disk. ikeep is the traditional XFS | |
70 | behaviour. When noikeep is specified, empty inode clusters | |
f6e9f288 JS |
71 | are returned to the free space pool. The default is noikeep for |
72 | non-DMAPI mounts, while ikeep is the default when DMAPI is in use. | |
1da177e4 | 73 | |
fc97bbf3 NS |
74 | inode64 |
75 | Indicates that XFS is allowed to create inodes at any location | |
76 | in the filesystem, including those which will result in inode | |
77 | numbers occupying more than 32 bits of significance. This is | |
c99abb8f CM |
78 | the default allocation option. Applications which do not handle |
79 | inode numbers bigger than 32 bits, should use inode32 option. | |
80 | ||
81 | inode32 | |
82 | Indicates that XFS is limited to create inodes at locations which | |
83 | will not result in inode numbers with more than 32 bits of | |
84 | significance. This is provided for backwards compatibility, since | |
85 | 64 bits inode numbers might cause problems for some applications | |
86 | that cannot handle large inode numbers. | |
fc97bbf3 NS |
87 | |
88 | largeio/nolargeio | |
89 | If "nolargeio" is specified, the optimal I/O reported in | |
90 | st_blksize by stat(2) will be as small as possible to allow user | |
91 | applications to avoid inefficient read/modify/write I/O. | |
92 | If "largeio" specified, a filesystem that has a "swidth" specified | |
93 | will return the "swidth" value (in bytes) in st_blksize. If the | |
94 | filesystem does not have a "swidth" specified but does specify | |
95 | an "allocsize" then "allocsize" (in bytes) will be returned | |
96 | instead. | |
97 | If neither of these two options are specified, then filesystem | |
98 | will behave as if "nolargeio" was specified. | |
99 | ||
1da177e4 LT |
100 | logbufs=value |
101 | Set the number of in-memory log buffers. Valid numbers range | |
102 | from 2-8 inclusive. | |
103 | The default value is 8 buffers for filesystems with a | |
fc97bbf3 NS |
104 | blocksize of 64KiB, 4 buffers for filesystems with a blocksize |
105 | of 32KiB, 3 buffers for filesystems with a blocksize of 16KiB | |
1da177e4 LT |
106 | and 2 buffers for all other configurations. Increasing the |
107 | number of buffers may increase performance on some workloads | |
108 | at the cost of the memory used for the additional log buffers | |
109 | and their associated control structures. | |
110 | ||
111 | logbsize=value | |
112 | Set the size of each in-memory log buffer. | |
113 | Size may be specified in bytes, or in kilobytes with a "k" suffix. | |
fc97bbf3 NS |
114 | Valid sizes for version 1 and version 2 logs are 16384 (16k) and |
115 | 32768 (32k). Valid sizes for version 2 logs also include | |
1da177e4 | 116 | 65536 (64k), 131072 (128k) and 262144 (256k). |
fc97bbf3 | 117 | The default value for machines with more than 32MiB of memory |
1da177e4 LT |
118 | is 32768, machines with less memory use 16384 by default. |
119 | ||
120 | logdev=device and rtdev=device | |
121 | Use an external log (metadata journal) and/or real-time device. | |
122 | An XFS filesystem has up to three parts: a data section, a log | |
123 | section, and a real-time section. The real-time section is | |
124 | optional, and the log section can be separate from the data | |
125 | section or contained within it. | |
126 | ||
fc97bbf3 NS |
127 | mtpt=mountpoint |
128 | Use with the "dmapi" option. The value specified here will be | |
129 | included in the DMAPI mount event, and should be the path of | |
130 | the actual mountpoint that is used. | |
131 | ||
1da177e4 LT |
132 | noalign |
133 | Data allocations will not be aligned at stripe unit boundaries. | |
134 | ||
135 | noatime | |
136 | Access timestamps are not updated when a file is read. | |
137 | ||
138 | norecovery | |
139 | The filesystem will be mounted without running log recovery. | |
140 | If the filesystem was not cleanly unmounted, it is likely to | |
141 | be inconsistent when mounted in "norecovery" mode. | |
142 | Some files or directories may not be accessible because of this. | |
143 | Filesystems mounted "norecovery" must be mounted read-only or | |
144 | the mount will fail. | |
145 | ||
146 | nouuid | |
147 | Don't check for double mounted file systems using the file system uuid. | |
148 | This is useful to mount LVM snapshot volumes. | |
149 | ||
fc97bbf3 | 150 | uquota/usrquota/uqnoenforce/quota |
1da177e4 | 151 | User disk quota accounting enabled, and limits (optionally) |
fc97bbf3 | 152 | enforced. Refer to xfs_quota(8) for further details. |
1da177e4 | 153 | |
fc97bbf3 | 154 | gquota/grpquota/gqnoenforce |
1da177e4 | 155 | Group disk quota accounting enabled and limits (optionally) |
fc97bbf3 NS |
156 | enforced. Refer to xfs_quota(8) for further details. |
157 | ||
158 | pquota/prjquota/pqnoenforce | |
159 | Project disk quota accounting enabled and limits (optionally) | |
160 | enforced. Refer to xfs_quota(8) for further details. | |
1da177e4 LT |
161 | |
162 | sunit=value and swidth=value | |
163 | Used to specify the stripe unit and width for a RAID device or | |
164 | a stripe volume. "value" must be specified in 512-byte block | |
165 | units. | |
166 | If this option is not specified and the filesystem was made on | |
167 | a stripe volume or the stripe width or unit were specified for | |
168 | the RAID device at mkfs time, then the mount system call will | |
169 | restore the value from the superblock. For filesystems that | |
170 | are made directly on RAID devices, these options can be used | |
171 | to override the information in the superblock if the underlying | |
172 | disk layout changes after the filesystem has been created. | |
173 | The "swidth" option is required if the "sunit" option has been | |
174 | specified, and must be a multiple of the "sunit" value. | |
175 | ||
fc97bbf3 NS |
176 | swalloc |
177 | Data allocations will be rounded up to stripe width boundaries | |
178 | when the current end of file is being extended and the file | |
179 | size is larger than the stripe width size. | |
180 | ||
181 | ||
1da177e4 LT |
182 | sysctls |
183 | ======= | |
184 | ||
185 | The following sysctls are available for the XFS filesystem: | |
186 | ||
187 | fs.xfs.stats_clear (Min: 0 Default: 0 Max: 1) | |
fc97bbf3 | 188 | Setting this to "1" clears accumulated XFS statistics |
1da177e4 | 189 | in /proc/fs/xfs/stat. It then immediately resets to "0". |
fc97bbf3 | 190 | |
1da177e4 LT |
191 | fs.xfs.xfssyncd_centisecs (Min: 100 Default: 3000 Max: 720000) |
192 | The interval at which the xfssyncd thread flushes metadata | |
193 | out to disk. This thread will flush log activity out, and | |
194 | do some processing on unlinked inodes. | |
195 | ||
196 | fs.xfs.xfsbufd_centisecs (Min: 50 Default: 100 Max: 3000) | |
197 | The interval at which xfsbufd scans the dirty metadata buffers list. | |
198 | ||
199 | fs.xfs.age_buffer_centisecs (Min: 100 Default: 1500 Max: 720000) | |
200 | The age at which xfsbufd flushes dirty metadata buffers to disk. | |
201 | ||
202 | fs.xfs.error_level (Min: 0 Default: 3 Max: 11) | |
203 | A volume knob for error reporting when internal errors occur. | |
204 | This will generate detailed messages & backtraces for filesystem | |
205 | shutdowns, for example. Current threshold values are: | |
206 | ||
207 | XFS_ERRLEVEL_OFF: 0 | |
208 | XFS_ERRLEVEL_LOW: 1 | |
209 | XFS_ERRLEVEL_HIGH: 5 | |
210 | ||
211 | fs.xfs.panic_mask (Min: 0 Default: 0 Max: 127) | |
fc97bbf3 | 212 | Causes certain error conditions to call BUG(). Value is a bitmask; |
1da177e4 | 213 | AND together the tags which represent errors which should cause panics: |
fc97bbf3 | 214 | |
1da177e4 LT |
215 | XFS_NO_PTAG 0 |
216 | XFS_PTAG_IFLUSH 0x00000001 | |
217 | XFS_PTAG_LOGRES 0x00000002 | |
218 | XFS_PTAG_AILDELETE 0x00000004 | |
219 | XFS_PTAG_ERROR_REPORT 0x00000008 | |
220 | XFS_PTAG_SHUTDOWN_CORRUPT 0x00000010 | |
221 | XFS_PTAG_SHUTDOWN_IOERROR 0x00000020 | |
222 | XFS_PTAG_SHUTDOWN_LOGERROR 0x00000040 | |
223 | ||
fc97bbf3 | 224 | This option is intended for debugging only. |
1da177e4 LT |
225 | |
226 | fs.xfs.irix_symlink_mode (Min: 0 Default: 0 Max: 1) | |
227 | Controls whether symlinks are created with mode 0777 (default) | |
228 | or whether their mode is affected by the umask (irix mode). | |
229 | ||
230 | fs.xfs.irix_sgid_inherit (Min: 0 Default: 0 Max: 1) | |
231 | Controls files created in SGID directories. | |
232 | If the group ID of the new file does not match the effective group | |
fc97bbf3 NS |
233 | ID or one of the supplementary group IDs of the parent dir, the |
234 | ISGID bit is cleared if the irix_sgid_inherit compatibility sysctl | |
1da177e4 LT |
235 | is set. |
236 | ||
fc97bbf3 NS |
237 | fs.xfs.inherit_sync (Min: 0 Default: 1 Max: 1) |
238 | Setting this to "1" will cause the "sync" flag set | |
239 | by the xfs_io(8) chattr command on a directory to be | |
1da177e4 LT |
240 | inherited by files in that directory. |
241 | ||
fc97bbf3 NS |
242 | fs.xfs.inherit_nodump (Min: 0 Default: 1 Max: 1) |
243 | Setting this to "1" will cause the "nodump" flag set | |
244 | by the xfs_io(8) chattr command on a directory to be | |
1da177e4 LT |
245 | inherited by files in that directory. |
246 | ||
fc97bbf3 NS |
247 | fs.xfs.inherit_noatime (Min: 0 Default: 1 Max: 1) |
248 | Setting this to "1" will cause the "noatime" flag set | |
249 | by the xfs_io(8) chattr command on a directory to be | |
1da177e4 | 250 | inherited by files in that directory. |
fc97bbf3 NS |
251 | |
252 | fs.xfs.inherit_nosymlinks (Min: 0 Default: 1 Max: 1) | |
253 | Setting this to "1" will cause the "nosymlinks" flag set | |
254 | by the xfs_io(8) chattr command on a directory to be | |
255 | inherited by files in that directory. | |
256 | ||
257 | fs.xfs.rotorstep (Min: 1 Default: 1 Max: 256) | |
258 | In "inode32" allocation mode, this option determines how many | |
259 | files the allocator attempts to allocate in the same allocation | |
260 | group before moving to the next allocation group. The intent | |
261 | is to control the rate at which the allocator moves between | |
262 | allocation groups when allocating extents for new files. |