-V, --version
Output version.
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-h, --help
Print a help message.
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-v, --verbose
Verbose mode.
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-a, --all
Mount all filesystems (of the given types) mentioned in fstab.
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-F, --fork
(Used in conjunction with -a.) Fork off a new incarnation of mount for each device. This will do
the mounts on different devices or different NFS servers in parallel. This has the advantage that
it is faster; also NFS timeouts go in parallel. A disadvantage is that the mounts are done in
undefined order. Thus, you cannot use this option if you want to mount both /usr and /usr/spool.
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-f, --fake
Causes everything to be done except for the actual system call; if it's not obvious, this
``fakes'' mounting the filesystem. This option is useful in conjunction with the -v flag to
determine what the mount command is trying to do. It can also be used to add entries for devices
that were mounted earlier with the -n option. The -f option checks for existing record in
/etc/mtab and fails when the record already exists (with regular non-fake mount, this check is
done by kernel).
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-i, --internal-only
Don't call the /sbin/mount.<filesystem> helper even if it exists.
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-l Add the labels in the mount output. Mount must have permission to read the disk device (e.g. be
suid root) for this to work. One can set such a label for ext2, ext3 or ext4 using the e2label(8)
utility, or for XFS using xfs_admin(8), or for reiserfs using reiserfstune(8).
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-n, --no-mtab
Mount without writing in /etc/mtab. This is necessary for example when /etc is on a read-only
filesystem.
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--no-canonicalize
Don't canonicalize paths. The mount command canonicalizes all paths (from command line or fstab)
and stores canonicalized paths to the /etc/mtab file. This option can be used together with the -f
flag for already canonicalized absolut paths.
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-p, --pass-fd num
In case of a loop mount with encryption, read the passphrase from file descriptor num instead of
from the terminal.
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-s Tolerate sloppy mount options rather than failing. This will ignore mount options not supported by
a filesystem type. Not all filesystems support this option. This option exists for support of the
Linux autofs-based automounter.
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-r, --read-only
Mount the filesystem read-only. A synonym is -o ro.
Note that, depending on the filesystem type, state and kernel behavior, the system may still write
to the device. For example, Ext3 or ext4 will replay its journal if the filesystem is dirty. To
prevent this kind of write access, you may want to mount ext3 or ext4 filesystem with "ro,noload"
mount options or set the block device to read-only mode, see command blockdev(8).
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-w, --rw
Mount the filesystem read/write. This is the default. A synonym is -o rw.
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-L label
Mount the partition that has the specified label.
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-U uuid
Mount the partition that has the specified uuid. These two options require the file
/proc/partitions (present since Linux 2.1.116) to exist.
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-t, --types vfstype
The argument following the -t is used to indicate the filesystem type. The filesystem types which
are currently supported include: adfs, affs, autofs, cifs, coda, coherent, cramfs, debugfs,
devpts, efs, ext, ext2, ext3, ext4, hfs, hfsplus, hpfs, iso9660, jfs, minix, msdos, ncpfs, nfs,
nfs4, ntfs, proc, qnx4, ramfs, reiserfs, romfs, squashfs, smbfs, sysv, tmpfs, ubifs, udf, ufs,
umsdos, usbfs, vfat, xenix, xfs, xiafs. Note that coherent, sysv and xenix are equivalent and
that xenix and coherent will be removed at some point in the future — use sysv instead. Since
kernel version 2.1.21 the types ext and xiafs do not exist anymore. Earlier, usbfs was known as
usbdevfs. Note, the real list of all supported filesystems depends on your kernel.
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-O, --test-opts opts
Used in conjunction with -a, to limit the set of filesystems to which the -a is applied. Like -t
in this regard except that it is useless except in the context of -a. For example, the command:
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-o, --options opts
Options are specified with a -o flag followed by a comma separated string of options. For example:
mount LABEL=mydisk -o noatime,nouser
For more details, see FILESYSTEM INDEPENDENT MOUNT OPTIONS and FILESYSTEM SPECIFIC MOUNT OPTIONS
sections.
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-B, --bind
Remount a subtree somewhere else (so that its contents are available in both places). See above.
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-R, --rbind
Remount a subtree and all possible submounts somewhere else (so that its contents are available in
both places). See above.
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-M, --move
Move a subtree to some other place. See above.
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uid=value and gid=value
Set the owner and group of the files in the filesystem (default: uid=gid=0).
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ownmask=value and othmask=value
Set the permission mask for ADFS 'owner' permissions and 'other' permissions, respectively
(default: 0700 and 0077, respectively). See also
/usr/src/linux/Documentation/filesystems/adfs.txt.
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uid=value and gid=value
Set the owner and group of the root of the filesystem (default: uid=gid=0, but with option uid or
gid without specified value, the uid and gid of the current process are taken).
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setuid=value and setgid=value
Set the owner and group of all files.
mode=value
Set the mode of all files to value & 0777 disregarding the original permissions. Add search
permission to directories that have read permission. The value is given in octal.
protect
Do not allow any changes to the protection bits on the filesystem.
usemp Set uid and gid of the root of the filesystem to the uid and gid of the mount point upon the first
sync or umount, and then clear this option. Strange...
verbose
Print an informational message for each successful mount.
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prefix=string
Prefix used before volume name, when following a link.
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volume=string
Prefix (of length at most 30) used before '/' when following a symbolic link.
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reserved=value
(Default: 2.) Number of unused blocks at the start of the device.
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root=value
Give explicitly the location of the root block.
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bs=value
Give blocksize. Allowed values are 512, 1024, 2048, 4096.
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mode=value
Set the mode of newly created PTYs to the specified value. The default is 0600. A value of
mode=620 and gid=5 makes "mesg y" the default on newly created PTYs.
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sb=n Instead of block 1, use block n as superblock. This could be useful when the filesystem has been
damaged. (Earlier, copies of the superblock would be made every 8192 blocks: in block 1, 8193,
16385, ... (and one got thousands of copies on a big filesystem). Since version 1.08, mke2fs has a
-s (sparse superblock) option to reduce the number of backup superblocks, and since version 1.15
this is the default. Note that this may mean that ext2 filesystems created by a recent mke2fs
cannot be mounted r/w under Linux 2.0.*.) The block number here uses 1k units. Thus, if you want
to use logical block 32768 on a filesystem with 4k blocks, use "sb=131072".
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journal=update
Update the ext3 filesystem's journal to the current format.
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journal=inum
When a journal already exists, this option is ignored. Otherwise, it specifies the number of the
inode which will represent the ext3 filesystem's journal file; ext3 will create a new journal,
overwriting the old contents of the file whose inode number is inum.
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barrier=0 / barrier=1
This enables/disables barriers. barrier=0 disables it, barrier=1 enables it. Write barriers
enforce proper on-disk ordering of journal commits, making volatile disk write caches safe to use,
at some performance penalty. The ext3 filesystem does not enable write barriers by default. Be
sure to enable barriers unless your disks are battery-backed one way or another. Otherwise you
risk filesystem corruption in case of power failure.
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commit=nrsec
Sync all data and metadata every nrsec seconds. The default value is 5 seconds. Zero means
default.
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journal=update
Update the ext4 filesystem's journal to the current format.
barrier=0 / barrier=1 / barrier / nobarrier
This enables/disables the use of write barriers in the jbd code. barrier=0 disables, barrier=1
enables. This also requires an IO stack which can support barriers, and if jbd gets an error on a
barrier write, it will disable again with a warning. Write barriers enforce proper on-disk
ordering of journal commits, making volatile disk write caches safe to use, at some performance
penalty. If your disks are battery-backed in one way or another, disabling barriers may safely
improve performance. The mount options "barrier" and "nobarrier" can also be used to enable or
disable barriers, for consistency with other ext4 mount options.
The ext4 filesystem enables write barriers by default.
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inode_readahead=n
This tuning parameter controls the maximum number of inode table blocks that ext4's inode table
readahead algorithm will pre-read into the buffer cache. The default value is 32 blocks.
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stripe=n
Number of filesystem blocks that mballoc will try to use for allocation size and alignment. For
RAID5/6 systems this should be the number of data disks * RAID chunk size in filesystem blocks.
delalloc
Deferring block allocation until write-out time.
nodelalloc
Disable delayed allocation. Blocks are allocated when data is copied from user to page cache.
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max_batch_time=usec
Maximum amount of time ext4 should wait for additional filesystem operations to be batch together
with a synchronous write operation. Since a synchronous write operation is going to force a commit
and then a wait for the I/O complete, it doesn't cost much, and can be a huge throughput win, we
wait for a small amount of time to see if any other transactions can piggyback on the synchronous
write. The algorithm used is designed to automatically tune for the speed of the disk, by
measuring the amount of time (on average) that it takes to finish committing a transaction. Call
this time the "commit time". If the time that the transaction has been running is less than the
commit time, ext4 will try sleeping for the commit time to see if other operations will join the
transaction. The commit time is capped by the max_batch_time, which defaults to 15000us (15ms).
This optimization can be turned off entirely by setting max_batch_time to 0.
min_batch_time=usec
This parameter sets the commit time (as described above) to be at least min_batch_time. It
defaults to zero microseconds. Increasing this parameter may improve the throughput of multi-
threaded, synchronous workloads on very fast disks, at the cost of increasing latency.
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journal_ioprio=prio
The I/O priority (from 0 to 7, where 0 is the highest priorty) which should be used for I/O
operations submitted by kjournald2 during a commit operation. This defaults to 3, which is a
slightly higher priority than the default I/O priority.
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uid=value and gid=value
Set the owner and group of all files. (Default: the uid and gid of the current process.)
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umask=value
Set the umask (the bitmask of the permissions that are not present). The default is the umask of
the current process. The value is given in octal.
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dmask=value
Set the umask applied to directories only. The default is the umask of the current process. The
value is given in octal.
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fmask=value
Set the umask applied to regular files only. The default is the umask of the current process.
The value is given in octal.
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allow_utime=value
This option controls the permission check of mtime/atime.
20 If current process is in group of file's group ID, you can change timestamp.
2 Other users can change timestamp.
The default is set from `dmask' option. (If the directory is writable, utime(2) is also allowed.
I.e. ~dmask & 022)
Normally utime(2) checks current process is owner of the file, or it has CAP_FOWNER capability.
But FAT filesystem doesn't have uid/gid on disk, so normal check is too unflexible. With this
option you can relax it.
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check=value
Three different levels of pickyness can be chosen:
r[elaxed]
Upper and lower case are accepted and equivalent, long name parts are truncated (e.g.
verylongname.foobar becomes verylong.foo), leading and embedded spaces are accepted in each
name part (name and extension).
n[ormal]
Like "relaxed", but many special characters (*, ?, <, spaces, etc.) are rejected. This is
the default.
s[trict]
Like "normal", but names may not contain long parts and special characters that are
sometimes used on Linux, but are not accepted by MS-DOS are rejected. (+, =, spaces, etc.)
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codepage=value
Sets the codepage for converting to shortname characters on FAT and VFAT filesystems. By default,
codepage 437 is used.
conv={b[inary]|t[ext]|a[uto]}
The fat filesystem can perform CRLF<-->NL (MS-DOS text format to UNIX text format) conversion in
the kernel. The following conversion modes are available:
binary no translation is performed. This is the default.
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cvf_option=option
Option passed to the CVF module. This option is obsolete.
debug Turn on the debug flag. A version string and a list of filesystem parameters will be printed
(these data are also printed if the parameters appear to be inconsistent).
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iocharset=value
Character set to use for converting between 8 bit characters and 16 bit Unicode characters. The
default is iso8859-1. Long filenames are stored on disk in Unicode format.
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creator=cccc, type=cccc
Set the creator/type values as shown by the MacOS finder used for creating new files. Default
values: '????'.
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uid=n, gid=n
Set the owner and group of all files. (Default: the uid and gid of the current process.)
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dir_umask=n, file_umask=n, umask=n
Set the umask used for all directories, all regular files, or all files and directories. Defaults
to the umask of the current process.
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session=n
Select the CDROM session to mount. Defaults to leaving that decision to the CDROM driver. This
option will fail with anything but a CDROM as underlying device.
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uid=value and gid=value
Set the owner and group of all files. (Default: the uid and gid of the current process.)
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umask=value
Set the umask (the bitmask of the permissions that are not present). The default is the umask of
the current process. The value is given in octal.
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uid=value and gid=value
Give all files in the filesystem the indicated user or group id, possibly overriding the
information found in the Rock Ridge extensions. (Default: uid=0,gid=0.)
map={n[ormal]|o[ff]|a[corn]}
For non-Rock Ridge volumes, normal name translation maps upper to lower case ASCII, drops a
trailing `;1', and converts `;' to `.'. With map=off no name translation is done. See norock.
(Default: map=normal.) map=acorn is like map=normal but also apply Acorn extensions if present.
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mode=value
For non-Rock Ridge volumes, give all files the indicated mode. (Default: read permission for
everybody.) Since Linux 2.1.37 one no longer needs to specify the mode in decimal. (Octal is
indicated by a leading 0.)
unhide Also show hidden and associated files. (If the ordinary files and the associated or hidden files
have the same filenames, this may make the ordinary files inaccessible.)
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session=x
Select number of session on multisession CD. (Since 2.3.4.)
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sbsector=xxx
Session begins from sector xxx. (Since 2.3.4.)
The following options are the same as for vfat and specifying them only makes sense when using discs
encoded using Microsoft's Joliet extensions.
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iocharset=value
Character set to use for converting 16 bit Unicode characters on CD to 8 bit characters. The
default is iso8859-1.
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resize=value
Resize the volume to value blocks. JFS only supports growing a volume, not shrinking it. This
option is only valid during a remount, when the volume is mounted read-write. The resize keyword
with no value will grow the volume to the full size of the partition.
nointegrity
Do not write to the journal. The primary use of this option is to allow for higher performance
when restoring a volume from backup media. The integrity of the volume is not guaranteed if the
system abnormally abends.
integrity
Default. Commit metadata changes to the journal. Use this option to remount a volume where the
nointegrity option was previously specified in order to restore normal behavior.
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iocharset=name
Character set to use when returning file names. Unlike VFAT, NTFS suppresses names that contain
nonconvertible characters. Deprecated.
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nls=name
New name for the option earlier called iocharset.
utf8 Use UTF-8 for converting file names.
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uid=value and gid=value
These options are recognized, but have no effect as far as I can see.
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resize=number
A remount option which permits online expansion of reiserfs partitions. Instructs reiserfs to
assume that the device has number blocks. This option is designed for use with devices which are
under logical volume management (LVM). There is a special resizer utility which can be obtained
from ftp://ftp.namesys.com/pub/reiserfsprogs.
user_xattr
Enable Extended User Attributes. See the attr(5) manual page.
acl Enable POSIX Access Control Lists. See the acl(5) manual page.
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barrier=none / barrier=flush
This enables/disables the use of write barriers in the journaling code. barrier=none disables it,
barrier=flush enables it. Write barriers enforce proper on-disk ordering of journal commits,
making volatile disk write caches safe to use, at some performance penalty. The reiserfs
filesystem does not enable write barriers by default. Be sure to enable barriers unless your disks
are battery-backed one way or another. Otherwise you risk filesystem corruption in case of power
failure.
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nr_blocks=
The same as size, but in blocks of PAGE_CACHE_SIZE
nr_inodes=
The maximum number of inodes for this instance. The default is half of the number of your physical
RAM pages, or (on a machine with highmem) the number of lowmem RAM pages, whichever is the lower.
The tmpfs mount options for sizing ( size, nr_blocks, and nr_inodes) accept a suffix k, m or g for Ki,
Mi, Gi (binary kilo, mega and giga) and can be changed on remount.
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mode= Set initial permissions of the root directory.
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gid= Set the default group.
umask= Set the default umask. The value is given in octal.
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uid= Set the default user.
unhide Show otherwise hidden files.
undelete
Show deleted files in lists.
nostrict
Unset strict conformance.
iocharset
Set the NLS character set.
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bs= Set the block size. (May not work unless 2048.)
novrs Skip volume sequence recognition.
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session=
Set the CDROM session counting from 0. Default: last session.
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anchor=
Override standard anchor location. Default: 256.
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volume=
Override the VolumeDesc location. (unused)
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partition=
Override the PartitionDesc location. (unused)
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lastblock=
Set the last block of the filesystem.
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fileset=
Override the fileset block location. (unused)
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rootdir=
Override the root directory location. (unused)
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ufstype=value
UFS is a filesystem widely used in different operating systems. The problem are differences among
implementations. Features of some implementations are undocumented, so its hard to recognize the
type of ufs automatically. That's why the user must specify the type of ufs by mount option.
Possible values are:
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onerror=value
Set behaviour on error:
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ihashsize=value
Sets the number of hash buckets available for hashing the in-memory inodes of the specified mount
point. If a value of zero is used, the value selected by the default algorithm will be displayed
in /proc/mounts.
ikeep|noikeep
When inode clusters are emptied of inodes, keep them around on the disk (ikeep) - this is the
traditional XFS behaviour and is still the default for now. Using the noikeep option, inode
clusters are returned to the free space pool.
inode64
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. This is provided
for backwards compatibility, but causes problems for backup applications that cannot handle large
inode numbers.
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. If largeio is
specified, a filesystem that has 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. If neither of these two options are specified,
then filesystem will behave as if nolargeio was specified.
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logbufs=value
Set the number of in-memory log buffers. Valid numbers range from 2-8 inclusive. The default
value is 8 buffers for any recent kernel.
logbsize=value
Set the size of each in-memory log buffer. Size may be specified in bytes, or in kilobytes with a
"k" suffix. Valid sizes for version 1 and version 2 logs are 16384 (16k) and 32768 (32k). Valid
sizes for version 2 logs also include 65536 (64k), 131072 (128k) and 262144 (256k). The default
value for any recent kernel is 32768.
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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. Refer to
xfs(5).
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mtpt=mountpoint
Use with the dmapi option. The value specified here will be included in the DMAPI mount event, and
should be the path of the actual mountpoint that is used.
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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. If this option is not specified and the filesystem was made on
a stripe volume or the stripe width or unit were specified for the RAID device at mkfs time, then
the mount system call will restore the value from the superblock. For filesystems that are made
directly on RAID devices, these options can be used to override the information in the superblock
if the underlying disk layout changes after the filesystem has been created. The swidth option is
required if the sunit option has been specified, and must be a multiple of the sunit value.
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