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