Based on kernel version 2.6.26. Page generated on 2008-07-16 21:12 EST.
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 Sets the number of hash buckets available for hashing the 56 in-memory inodes of the specified mount point. If a value 57 of zero is used, the value selected by the default algorithm 58 will be displayed in /proc/mounts. 59 60 ikeep/noikeep 61 When inode clusters are emptied of inodes, keep them around 62 on the disk (ikeep) - this is the traditional XFS behaviour 63 and is still the default for now. Using the noikeep option, 64 inode clusters are returned to the free space pool. 65 66 inode64 67 Indicates that XFS is allowed to create inodes at any location 68 in the filesystem, including those which will result in inode 69 numbers occupying more than 32 bits of significance. This is 70 provided for backwards compatibility, but causes problems for 71 backup applications that cannot handle large inode numbers. 72 73 largeio/nolargeio 74 If "nolargeio" is specified, the optimal I/O reported in 75 st_blksize by stat(2) will be as small as possible to allow user 76 applications to avoid inefficient read/modify/write I/O. 77 If "largeio" specified, a filesystem that has a "swidth" specified 78 will return the "swidth" value (in bytes) in st_blksize. If the 79 filesystem does not have a "swidth" specified but does specify 80 an "allocsize" then "allocsize" (in bytes) will be returned 81 instead. 82 If neither of these two options are specified, then filesystem 83 will behave as if "nolargeio" was specified. 84 85 logbufs=value 86 Set the number of in-memory log buffers. Valid numbers range 87 from 2-8 inclusive. 88 The default value is 8 buffers for filesystems with a 89 blocksize of 64KiB, 4 buffers for filesystems with a blocksize 90 of 32KiB, 3 buffers for filesystems with a blocksize of 16KiB 91 and 2 buffers for all other configurations. Increasing the 92 number of buffers may increase performance on some workloads 93 at the cost of the memory used for the additional log buffers 94 and their associated control structures. 95 96 logbsize=value 97 Set the size of each in-memory log buffer. 98 Size may be specified in bytes, or in kilobytes with a "k" suffix. 99 Valid sizes for version 1 and version 2 logs are 16384 (16k) and 100 32768 (32k). Valid sizes for version 2 logs also include 101 65536 (64k), 131072 (128k) and 262144 (256k). 102 The default value for machines with more than 32MiB of memory 103 is 32768, machines with less memory use 16384 by default. 104 105 logdev=device and rtdev=device 106 Use an external log (metadata journal) and/or real-time device. 107 An XFS filesystem has up to three parts: a data section, a log 108 section, and a real-time section. The real-time section is 109 optional, and the log section can be separate from the data 110 section or contained within it. 111 112 mtpt=mountpoint 113 Use with the "dmapi" option. The value specified here will be 114 included in the DMAPI mount event, and should be the path of 115 the actual mountpoint that is used. 116 117 noalign 118 Data allocations will not be aligned at stripe unit boundaries. 119 120 noatime 121 Access timestamps are not updated when a file is read. 122 123 norecovery 124 The filesystem will be mounted without running log recovery. 125 If the filesystem was not cleanly unmounted, it is likely to 126 be inconsistent when mounted in "norecovery" mode. 127 Some files or directories may not be accessible because of this. 128 Filesystems mounted "norecovery" must be mounted read-only or 129 the mount will fail. 130 131 nouuid 132 Don't check for double mounted file systems using the file system uuid. 133 This is useful to mount LVM snapshot volumes. 134 135 osyncisosync 136 Make O_SYNC writes implement true O_SYNC. WITHOUT this option, 137 Linux XFS behaves as if an "osyncisdsync" option is used, 138 which will make writes to files opened with the O_SYNC flag set 139 behave as if the O_DSYNC flag had been used instead. 140 This can result in better performance without compromising 141 data safety. 142 However if this option is not in effect, timestamp updates from 143 O_SYNC writes can be lost if the system crashes. 144 If timestamp updates are critical, use the osyncisosync option. 145 146 uquota/usrquota/uqnoenforce/quota 147 User disk quota accounting enabled, and limits (optionally) 148 enforced. Refer to xfs_quota(8) for further details. 149 150 gquota/grpquota/gqnoenforce 151 Group disk quota accounting enabled and limits (optionally) 152 enforced. Refer to xfs_quota(8) for further details. 153 154 pquota/prjquota/pqnoenforce 155 Project disk quota accounting enabled and limits (optionally) 156 enforced. Refer to xfs_quota(8) for further details. 157 158 sunit=value and swidth=value 159 Used to specify the stripe unit and width for a RAID device or 160 a stripe volume. "value" must be specified in 512-byte block 161 units. 162 If this option is not specified and the filesystem was made on 163 a stripe volume or the stripe width or unit were specified for 164 the RAID device at mkfs time, then the mount system call will 165 restore the value from the superblock. For filesystems that 166 are made directly on RAID devices, these options can be used 167 to override the information in the superblock if the underlying 168 disk layout changes after the filesystem has been created. 169 The "swidth" option is required if the "sunit" option has been 170 specified, and must be a multiple of the "sunit" value. 171 172 swalloc 173 Data allocations will be rounded up to stripe width boundaries 174 when the current end of file is being extended and the file 175 size is larger than the stripe width size. 176 177 178 sysctls 179 ======= 180 181 The following sysctls are available for the XFS filesystem: 182 183 fs.xfs.stats_clear (Min: 0 Default: 0 Max: 1) 184 Setting this to "1" clears accumulated XFS statistics 185 in /proc/fs/xfs/stat. It then immediately resets to "0". 186 187 fs.xfs.xfssyncd_centisecs (Min: 100 Default: 3000 Max: 720000) 188 The interval at which the xfssyncd thread flushes metadata 189 out to disk. This thread will flush log activity out, and 190 do some processing on unlinked inodes. 191 192 fs.xfs.xfsbufd_centisecs (Min: 50 Default: 100 Max: 3000) 193 The interval at which xfsbufd scans the dirty metadata buffers list. 194 195 fs.xfs.age_buffer_centisecs (Min: 100 Default: 1500 Max: 720000) 196 The age at which xfsbufd flushes dirty metadata buffers to disk. 197 198 fs.xfs.error_level (Min: 0 Default: 3 Max: 11) 199 A volume knob for error reporting when internal errors occur. 200 This will generate detailed messages & backtraces for filesystem 201 shutdowns, for example. Current threshold values are: 202 203 XFS_ERRLEVEL_OFF: 0 204 XFS_ERRLEVEL_LOW: 1 205 XFS_ERRLEVEL_HIGH: 5 206 207 fs.xfs.panic_mask (Min: 0 Default: 0 Max: 127) 208 Causes certain error conditions to call BUG(). Value is a bitmask; 209 AND together the tags which represent errors which should cause panics: 210 211 XFS_NO_PTAG 0 212 XFS_PTAG_IFLUSH 0x00000001 213 XFS_PTAG_LOGRES 0x00000002 214 XFS_PTAG_AILDELETE 0x00000004 215 XFS_PTAG_ERROR_REPORT 0x00000008 216 XFS_PTAG_SHUTDOWN_CORRUPT 0x00000010 217 XFS_PTAG_SHUTDOWN_IOERROR 0x00000020 218 XFS_PTAG_SHUTDOWN_LOGERROR 0x00000040 219 220 This option is intended for debugging only. 221 222 fs.xfs.irix_symlink_mode (Min: 0 Default: 0 Max: 1) 223 Controls whether symlinks are created with mode 0777 (default) 224 or whether their mode is affected by the umask (irix mode). 225 226 fs.xfs.irix_sgid_inherit (Min: 0 Default: 0 Max: 1) 227 Controls files created in SGID directories. 228 If the group ID of the new file does not match the effective group 229 ID or one of the supplementary group IDs of the parent dir, the 230 ISGID bit is cleared if the irix_sgid_inherit compatibility sysctl 231 is set. 232 233 fs.xfs.restrict_chown (Min: 0 Default: 1 Max: 1) 234 Controls whether unprivileged users can use chown to "give away" 235 a file to another user. 236 237 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 240 inherited by files in that directory. 241 242 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 245 inherited by files in that directory. 246 247 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 250 inherited by files in that directory. 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.