This is a straight cut and paste from the util-linux mount manpage to xfs.5. It's pretty much impossible for util-linux to keep up with every filesystem out there, and Karel has more than once expressed a wish that mount options move into fs-specific manpages. So, here we go. Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx> --- diff --git a/man/man5/xfs.5 b/man/man5/xfs.5 index 0f490f0..1729e38 100644 --- a/man/man5/xfs.5 +++ b/man/man5/xfs.5 @@ -1,6 +1,6 @@ .TH xfs 5 .SH NAME -xfs \- layout of the XFS filesystem +xfs \- layout and mount options for the XFS filesystem .SH DESCRIPTION An XFS filesystem can reside on a regular disk partition or on a logical volume. @@ -98,9 +98,205 @@ and by-handle (see .BR open_by_handle (3)) interfaces. .SH MOUNT OPTIONS -Refer to the +The following XFS-specific mount options may be used when mounting +an XFS filesystem. Other generic options may be used as well; refer to the .BR mount (8) -manual entry for descriptions of the individual XFS mount options. +manual page for more details. +.TP +.B allocsize=size +Sets the buffered I/O end-of-file preallocation size when +doing delayed allocation writeout. Valid values for this +option are page size (typically 4KiB) through to 1GiB, +inclusive, in power-of-2 increments. +.sp +The default behavior is for dynamic end-of-file +preallocation size, which uses a set of heuristics to +optimise the preallocation size based on the current +allocation patterns within the file and the access patterns +to the file. Specifying a fixed allocsize value turns off +the dynamic behavior. +.TP +.BR attr2 | noattr2 +The options enable/disable an "opportunistic" improvement to +be made in the way inline extended attributes are stored +on-disk. When the new form is used for the first time when +attr2 is selected (either when setting or removing extended +attributes) the on-disk superblock feature bit field will be +updated to reflect this format being in use. +.sp +The default behavior is determined by the on-disk feature +bit indicating that attr2 behavior is active. If either +mount option it set, then that becomes the new default used +by the filesystem. +.sp +CRC enabled filesystems always use the attr2 format, and so +will reject the noattr2 mount option if it is set. +.TP +.BR barrier | nobarrier +Enables/disables the use of block layer write barriers for +writes into the journal and for data integrity operations. +This allows for drive level write caching to be enabled, for +devices that support write barriers. +.TP +.BR discard | nodiscard +Enable/disable the issuing of commands to let the block +device reclaim space freed by the filesystem. This is +useful for SSD devices, thinly provisioned LUNs and virtual +machine images, but may have a performance impact. +.sp +Note: It is currently recommended that you use the fstrim +application to discard unused blocks rather than the discard +mount option because the performance impact of this option +is quite severe. +.TP +.BR grpid | bsdgroups | nogrpid | sysvgroups +These options define what group ID a newly created file +gets. When grpid is set, it takes the group ID of the +directory in which it is created; otherwise it takes the +fsgid of the current process, unless the directory has the +setgid bit set, in which case it takes the gid from the +parent directory, and also gets the setgid bit set if it is +a directory itself. +.TP +.B filestreams +Make the data allocator use the filestreams allocation mode +across the entire filesystem rather than just on directories +configured to use it. +.TP +.BR ikeep | noikeep +When ikeep is specified, XFS does not delete empty inode +clusters and keeps them around on disk. When noikeep is +specified, empty inode clusters are returned to the free +space pool. +.TP +.BR inode32 | inode64 +When inode32 is specified, it indicates that XFS limits +inode creation to locations which will not result in inode +numbers with more than 32 bits of significance. +.sp +When inode64 is specified, it indicates that XFS is allowed +to create inodes at any location in the filesystem, +including those which will result in inode numbers occupying +more than 32 bits of significance. +.sp +inode32 is provided for backwards compatibility with older +systems and applications, since 64 bits inode numbers might +cause problems for some applications that cannot handle +large inode numbers. If applications are in use which do +not handle inode numbers bigger than 32 bits, the inode32 +option should be specified. +.TP +.BR largeio | nolargeio +If "nolargeio" is specified, the optimal I/O reported in +st_blksize by stat(2) will be as small as possible to allow +user applications to avoid inefficient read/modify/write +I/O. This is typically the page size of the machine, as +this is the granularity of the page cache. +.sp +If "largeio" specified, a filesystem that was created with a +"swidth" specified will return the "swidth" value (in bytes) +in st_blksize. If the filesystem does not have a "swidth" +specified but does specify an "allocsize" then "allocsize" +(in bytes) will be returned instead. Otherwise the behavior +is the same as if "nolargeio" was specified. +.TP +.B logbufs=value +Set the number of in-memory log buffers. Valid numbers +range from 2\(en8 inclusive. +.sp +The default value is 8 buffers. +.sp +If the memory cost of 8 log buffers is too high on small +systems, then it may be reduced at some cost to performance +on metadata intensive workloads. The logbsize option below +controls the size of each buffer and so is also relevant to +this case. +.TP +.B logbsize=value +Set the size of each in-memory log buffer. The size may be +specified in bytes, or in kibibytes (KiB) with a "k" suffix. +Valid sizes for version 1 and version 2 logs are 16384 (value=16k) +and 32768 (value=32k). Valid sizes for version 2 logs also +include 65536 (value=64k), 131072 (value=128k) and 262144 (value=256k). The +logbsize must be an integer multiple of the log +stripe unit configured at mkfs time. +.sp +The default value for version 1 logs is 32768, while the +default value for version 2 logs is MAX(32768, log_sunit). +.TP +.BR logdev=device and rtdev=device +Use an external log (metadata journal) and/or real-time device. +An XFS filesystem has up to three parts: a data section, a log +section, and a real-time section. The real-time section is +optional, and the log section can be separate from the data +section or contained within it. +.TP +.B noalign +Data allocations will not be aligned at stripe unit +boundaries. This is only relevant to filesystems created +with non-zero data alignment parameters (sunit, swidth) by +mkfs. +.TP +.B norecovery +The filesystem will be mounted without running log recovery. +If the filesystem was not cleanly unmounted, it is likely to +be inconsistent when mounted in "norecovery" mode. +Some files or directories may not be accessible because of this. +Filesystems mounted "norecovery" must be mounted read-only or +the mount will fail. +.TP +.B nouuid +Don't check for double mounted file systems using the file +system uuid. This is useful to mount LVM snapshot volumes, +and often used in combination with "norecovery" for mounting +read-only snapshots. +.TP +.B noquota +Forcibly turns off all quota accounting and enforcement +within the filesystem. +.TP +.B uquota/usrquota/uqnoenforce/quota +User disk quota accounting enabled, and limits (optionally) +enforced. Refer to xfs_quota(8) for further details. +.TP +.B gquota/grpquota/gqnoenforce +Group disk quota accounting enabled and limits (optionally) +enforced. Refer to xfs_quota(8) for further details. +.TP +.B pquota/prjquota/pqnoenforce +Project disk quota accounting enabled and limits (optionally) +enforced. Refer to xfs_quota(8) for further details. +.TP +.BR sunit=value " and " swidth=value +Used to specify the stripe unit and width for a RAID device +or a stripe volume. "value" must be specified in 512-byte +block units. These options are only relevant to filesystems +that were created with non-zero data alignment parameters. +.sp +The sunit and swidth parameters specified must be compatible +with the existing filesystem alignment characteristics. In +general, that means the only valid changes to sunit are +increasing it by a power-of-2 multiple. Valid swidth values +are any integer multiple of a valid sunit value. +.sp +Typically the only time these mount options are necessary if +after an underlying RAID device has had it's geometry +modified, such as adding a new disk to a RAID5 lun and +reshaping it. +.TP +.B swalloc +Data allocations will be rounded up to stripe width boundaries +when the current end of file is being extended and the file +size is larger than the stripe width size. +.TP +.B wsync +When specified, all filesystem namespace operations are +executed synchronously. This ensures that when the namespace +operation (create, unlink, etc) completes, the change to the +namespace is on stable storage. This is useful in HA setups +where failover must not result in clients seeing +inconsistent namespace presentation during or after a +failover event. .SH SEE ALSO .BR xfsctl (3), .BR mount (8), _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
