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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 | |
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 | dmapi |
43 | Enable the DMAPI (Data Management API) event callouts. |
44 | Use with the "mtpt" option. |
45 | |
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. |
53 | |
54 | ihashsize=value |
55 | In memory inode hashes have been removed, so this option has |
56 | no function as of August 2007. Option is deprecated. |
57 | |
58 | ikeep/noikeep |
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. |
64 | |
65 | inode64 |
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. |
71 | |
72 | largeio/nolargeio |
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 |
80 | instead. |
81 | If neither of these two options are specified, then filesystem |
82 | will behave as if "nolargeio" was specified. |
83 | |
84 | logbufs=value |
85 | Set the number of in-memory log buffers. Valid numbers range |
86 | from 2-8 inclusive. |
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. |
94 | |
95 | logbsize=value |
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. |
103 | |
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. |
110 | |
111 | mtpt=mountpoint |
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. |
115 | |
116 | noalign |
117 | Data allocations will not be aligned at stripe unit boundaries. |
118 | |
119 | noatime |
120 | Access timestamps are not updated when a file is read. |
121 | |
122 | norecovery |
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 |
128 | the mount will fail. |
129 | |
130 | nouuid |
131 | Don't check for double mounted file systems using the file system uuid. |
132 | This is useful to mount LVM snapshot volumes. |
133 | |
134 | osyncisosync |
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 |
140 | data safety. |
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. |
144 | |
145 | uquota/usrquota/uqnoenforce/quota |
146 | User disk quota accounting enabled, and limits (optionally) |
147 | enforced. Refer to xfs_quota(8) for further details. |
148 | |
149 | gquota/grpquota/gqnoenforce |
150 | Group disk quota accounting enabled and limits (optionally) |
151 | enforced. Refer to xfs_quota(8) for further details. |
152 | |
153 | pquota/prjquota/pqnoenforce |
154 | Project disk quota accounting enabled and limits (optionally) |
155 | enforced. Refer to xfs_quota(8) for further details. |
156 | |
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 |
160 | units. |
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. |
170 | |
171 | swalloc |
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. |
175 | |
176 | |
177 | sysctls |
178 | ======= |
179 | |
180 | The following sysctls are available for the XFS filesystem: |
181 | |
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". |
185 | |
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. |
190 | |
191 | fs.xfs.xfsbufd_centisecs (Min: 50 Default: 100 Max: 3000) |
192 | The interval at which xfsbufd scans the dirty metadata buffers list. |
193 | |
194 | fs.xfs.age_buffer_centisecs (Min: 100 Default: 1500 Max: 720000) |
195 | The age at which xfsbufd flushes dirty metadata buffers to disk. |
196 | |
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: |
201 | |
202 | XFS_ERRLEVEL_OFF: 0 |
203 | XFS_ERRLEVEL_LOW: 1 |
204 | XFS_ERRLEVEL_HIGH: 5 |
205 | |
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: |
209 | |
210 | XFS_NO_PTAG 0 |
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 |
218 | |
219 | This option is intended for debugging only. |
220 | |
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). |
224 | |
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 |
230 | is set. |
231 | |
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. |
236 | |
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. |
241 | |
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. |
246 | |
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. |
251 | |
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. |
258 |
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