mount - mount a file system
SYNOPSIS
mount [-lhV]
mount -a [-fFnrsvw] [-t vfstype] [-O optlist]
mount [-fnrsvw] [-o options [,...]] device | dir
mount [-fnrsvw] [-t vfstype] [-o options] device dir
DESCRIPTION
All files accessible in a Unix system are arranged in one
big tree, the file hierarchy, rooted at /. These files
can be spread out over several devices. The mount command
serves to attach the file system found on some device to
the big file tree. Conversely, the umount(8) command will
detach it again.
The standard form of the mount command, is
mount -t type device dir
This tells the kernel to attach the file system found on
device (which is of type type) at the directory dir. The
previous contents (if any) and owner and mode of dir
become invisible, and as long as this file system remains
mounted, the pathname dir refers to the root of the file
system on device.
Three forms of invocation do not actually mount anything:
mount -h
prints a help message;
mount -V
prints a version string; and just
mount [-l] [-t type]
lists all mounted file systems (of type type). The option
-l adds the (ext2, ext3 and XFS) labels in this listing.
See below.
Since Linux 2.4.0 it is possible to remount part of the
file hierarchy somewhere else. The call is
mount --bind olddir newdir
The proc file system is not associated with a special
device, and when mounting it, an arbitrary keyword, such
as proc can be used instead of a device specification.
(The customary choice none is less fortunate: the error
message `none busy' from umount can be confusing.)
Most devices are indicated by a file name (of a block spe
cial device), like /dev/sda1, but there are other possi
bilities. For example, in the case of an NFS mount, device
may look like knuth.cwi.nl:/dir. It is possible to indi
cate a block special device using its volume label or UUID
(see the -L and -U options below).
describing what devices are usually mounted where, using
which options. This file is used in three ways:
(i) The command
mount -a [-t type] [-O optlist]
(usually given in a bootscript) causes all file systems
mentioned in fstab (of the proper type and/or having or
not having the proper options) to be mounted as indicated,
except for those whose line contains the noauto keyword.
Adding the -F option will make mount fork, so that the
filesystems are mounted simultaneously.
(ii) When mounting a file system mentioned in fstab, it
suffices to give only the device, or only the mount point.
(iii) Normally, only the superuser can mount file systems.
However, when fstab contains the user option on a line,
then anybody can mount the corresponding system.
Thus, given a line
/dev/cdrom /cd iso9660 ro,user,noauto,unhide
any user can mount the iso9660 file system found on his
CDROM using the command
mount /dev/cdrom
or
mount /cd
For more details, see fstab(5). Only the user that
mounted a filesystem can unmount it again. If any user
should be able to unmount, then use users instead of user
in the fstab line. The owner option is similar to the
user option, with the restriction that the user must be
the owner of the special file. This may be useful e.g. for
/dev/fd if a login script makes the console user owner of
this device.
The programs mount and umount maintain a list of currently
mounted file systems in the file /etc/mtab. If no argu
ments are given to mount, this list is printed. When the
proc filesystem is mounted (say at /proc), the files
/etc/mtab and /proc/mounts have very similar contents. The
former has somewhat more information, such as the mount
options used, but is not necessarily up-to-date (cf. the
-n option below). It is possible to replace /etc/mtab by a
symbolic link to /proc/mounts, but some information is
lost that way, and in particular working with the loop
device will be less convenient.
OPTIONS
The full set of options used by an invocation of mount is
determined by first extracting the options for the file
system from the fstab table, then applying any options
specified by the -o argument, and finally applying a -r or
Options available for the mount command:
-V Output version.
-h Print a help message.
-v Verbose mode.
-a Mount all filesystems (of the given types) men
tioned in fstab.
-F (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 unde
fined order. Thus, you cannot use this option if
you want to mount both /usr and /usr/spool.
-f Causes everything to be done except for the actual
system call; if it's not obvious, this ``fakes''
mounting the file system. 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 ear
lier with the -n option.
-l Add the ext2, ext3 and XFS labels in the mount out
put. 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 or ext3 using the
e2label(8) utility, or for XFS using xfs_admin(8).
-n Mount without writing in /etc/mtab. This is neces
sary for example when /etc is on a read-only file
system.
-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.
-r Mount the file system read-only. A synonym is -o
ro.
-w Mount the file system read/write. This is the
default. A synonym is -o rw.
-L label
Mount the partition that has the specified label.
Mount the partition that has the specified uuid.
These two options require the file /proc/partitions
(present since Linux 2.1.116) to exist.
-t vfstype
The argument following the -t is used to indicate
the file system type. The file system types which
are currently supported are: adfs, affs, autofs,
coda, coherent, cramfs, devpts, efs, ext, ext2,
ext3, hfs, hpfs, iso9660, minix, msdos, ncpfs, nfs,
ntfs, proc, qnx4, reiserfs, romfs, smbfs, sysv,
udf, ufs, umsdos, 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 ker
nel version 2.1.21 the types ext and xiafs do not
exist anymore.
For most types all the mount program has to do is
issue a simple mount(2) system call, and no
detailed knowledge of the filesystem type is
required. For a few types however (like nfs,
smbfs, ncpfs) ad hoc code is necessary. The nfs ad
hoc code is built in, but smbfs and ncpfs have a
separate mount program. In order to make it possi
ble to treat all types in a uniform way, mount will
execute the program /sbin/mount.TYPE (if that
exists) when called with type TYPE. Since various
versions of the smbmount program have different
calling conventions, /sbin/mount.smb may have to be
a shell script that sets up the desired call.
The type iso9660 is the default. If no -t option
is given, or if the auto type is specified, the
superblock is probed for the filesystem type
(minix, ext, ext2, ext3, xiafs, iso9660, reiserfs
,romfs, ufs, ntfs, qnx4, bfs, xfs, cramfs, hfs
,hpfs, adfs are supported). If this probe fails,
mount will try to read the file /etc/filesystems,
or, if that does not exist, /proc/filesystems. All
of the filesystem types listed there will be tried,
except for those that are labeled "nodev" (e.g.,
devpts, proc and nfs).
Note that the auto type may be useful for user-
mounted floppies. Creating a file /etc/filesystems
can be useful to change the probe order (e.g., to
try vfat before msdos) or if you use a kernel mod
ule autoloader. Warning: the probing uses a
heuristic (the presence of appropriate `magic'),
and could recognize the wrong filesystem type.
More than one type may be specified in a comma
be prefixed with no to specify the file system
types on which no action should be taken. (This
can be meaningful with the -a option.)
For example, the command:
mount -a -t nomsdos,ext
mounts all file systems except those of type msdos
and ext.
-O 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:
mount -a -O no_netdev
mounts all file systems except those which have the
option _netdev specified in the options field in
the /etc/fstab file.
It is different from -t in that each option is
matched exactly; a leading no at the beginning of
one option does not negate the rest. That is,
while
mount -a -t nomsdos,ext
mounts filesystems that are neither msdos nor ext
(the no applies to both msdos and ext2 filesystem
types),
mount -a -O no_netdev,user
mounts all filesystems that do not have the _netdev
option and do have the user option. In order to
specify neither _netdev nor user options, use:
mount -a -O no_netdev,nouser
The -t and -O options are cumulative in effect;
that is, the command
mount -a -t ext2 -O _netdev
mounts all ext2 filesystems with the _netdev
option, not all filesystems that are either ext2 or
have the _netdev option specified.
-o Options are specified with a -o flag followed by a
comma separated string of options. Some of these
options are only useful when they appear in the
/etc/fstab file. The following options apply to
any file system that is being mounted (but not
every file system actually honors them - e.g., the
sync option today has effect only for ext2, ext3
and ufs):
async All I/O to the file system should be done
asynchronously.
atime Update inode access time for each access.
This is the default.
defaults
Use default options: rw, suid, dev, exec,
auto, nouser, and async.
dev Interpret character or block special devices
on the file system.
exec Permit execution of binaries.
_netdev
The filesystem resides on a device that
requires network access (used to prevent the
system from attempting to mount these
filesystems until the network has been
enabled on the system).
noatime
Do not update inode access times on this
file system (e.g, for faster access on the
news spool to speed up news servers).
noauto Can only be mounted explicitly (i.e., the -a
option will not cause the file system to be
mounted).
nodev Do not interpret character or block special
devices on the file system.
noexec Do not allow execution of any binaries on
the mounted file system. This option might
be useful for a server that has file systems
containing binaries for architectures other
than its own.
nosuid Do not allow set-user-identifier or set-
group-identifier bits to take effect. (This
seems safe, but is in fact rather unsafe if
you have suidperl(1) installed.)
nouser Forbid an ordinary (i.e., non-root) user to
mount the file system. This is the default.
remount
Attempt to remount an already-mounted file
system. This is commonly used to change the
mount flags for a file system, especially to
make a readonly file system writeable. It
does not change device or mount point.
ro Mount the file system read-only.
rw Mount the file system read-write.
tifier bits to take effect.
sync All I/O to the file system should be done
synchronously.
user Allow an ordinary user to mount the file
system. This option implies the options
noexec, nosuid, and nodev (unless overridden
by subsequent options, as in the option line
user,exec,dev,suid).
FILESYSTEM SPECIFIC MOUNT OPTIONS
The following options apply only to certain file systems.
We sort them by file system. They all follow the -o flag.
Mount options for adfs
uid=value and gid=value
Set the owner and group of the files in the file
system (default: uid=gid=0).
ownmask=value and othmask=value
Set the permission mask for ADFS 'owner' permis
sions and 'other' permissions, respectively
(default: 0700 and 0077, respectively). See also
/usr/src/linux/Documentation/filesystems/adfs.txt.
Mount options for affs
uid=value and gid=value
Set the owner and group of the root of the file
system (default: uid=gid=0, but with option uid or
gid without specified value, the uid and gid of the
current process are taken).
setuid=value and setgid=value
Set the owner and group of all files.
mode=value
Set the mode of all files to value & 0777 disre
garding the original permissions. Add search per
mission to directories that have read permission.
The value is given in octal.
protect
Do not allow any changes to the protection bits on
the file system.
usemp Set uid and gid of the root of the file system to
the uid and gid of the mount point upon the first
sync or umount, and then clear this option.
Strange...
Print an informational message for each successful
mount.
prefix=string
Prefix used before volume name, when following a
link.
volume=string
Prefix (of length at most 30) used before '/' when
following a symbolic link.
reserved=value
(Default: 2.) Number of unused blocks at the start
of the device.
root=value
Give explicitly the location of the root block.
bs=value
Give blocksize. Allowed values are 512, 1024, 2048,
4096.
grpquota / noquota / quota / usrquota
These options are accepted but ignored. (However,
quota utilities may react to such strings in
/etc/fstab.)
Mount options for coherent
None.
Mount options for devpts
The devpts file system is a pseudo file system, tradition
ally mounted on /dev/pts. In order to acquire a pseudo
terminal, a process opens /dev/ptmx; the number of the
pseudo terminal is then made available to the process and
the pseudo terminal slave can be accessed as
/dev/pts/<number>.
uid=value and gid=value
This sets the owner or the group of newly created
PTYs to the specified values. When nothing is spec
ified, they will be set to the UID and GID of the
creating process. For example, if there is a tty
group with GID 5, then gid=5 will cause newly cre
ated PTYs to belong to the tty group.
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 cre
ated PTYs.
None. Note that the `ext' file system is obsolete. Don't
use it. Since Linux version 2.1.21 extfs is no longer
part of the kernel source.
Mount options for ext2
The `ext2' file system is the standard Linux file system.
Due to a kernel bug, it may be mounted with random mount
options (fixed in Linux 2.0.4).
bsddf / minixdf
Set the behaviour for the statfs system call. The
minixdf behaviour is to return in the f_blocks
field the total number of blocks of the file sys
tem, while the bsddf behaviour (which is the
default) is to subtract the overhead blocks used by
the ext2 file system and not available for file
storage. Thus
% mount /k -o minixdf; df /k; umount /k
Filesystem 1024-blocks Used Available Capacity Mounted on
/dev/sda6 2630655 86954 2412169 3% /k
% mount /k -o bsddf; df /k; umount /k
Filesystem 1024-blocks Used Available Capacity Mounted on
/dev/sda6 2543714 13 2412169 0% /k
(Note that this example shows that one can add command
line options to the options given in /etc/fstab.)
check / check=normal / check=strict
Set checking level. When at least one of these
options is set (and check=normal is set by default)
the inodes and blocks bitmaps are checked upon
mount (which can take half a minute or so on a big
disk, and is rather useless). With strict check
ing, block deallocation checks that the block to
free is in the data zone.
check=none / nocheck
No checking is done. This is fast. Recent kernels
do not have a check option anymore - checking with
e2fsck(8) is more meaningful.
debug Print debugging info upon each (re)mount.
errors=continue / errors=remount-ro / errors=panic
Define the behaviour when an error is encountered.
(Either ignore errors and just mark the file system
erroneous and continue, or remount the file system
read-only, or panic and halt the system.) The
default is set in the filesystem superblock, and
can be changed using tune2fs(8).
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; other
wise (the default) it takes the fsgid of the cur
rent 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.
resgid=n and resuid=n
The ext2 file system reserves a certain percentage
of the available space (by default 5%, see
mke2fs(8) and tune2fs(8)). These options determine
who can use the reserved blocks. (Roughly: whoever
has the specified uid, or belongs to the specified
group.)
sb=n Instead of block 1, use block n as superblock. This
could be useful when the filesystem has been dam
aged. (Earlier, copies of the superblock would be
made every 8192 blocks: in block 1, 8193, 16385,
... (and one got hundreds or even 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.*.)
grpquota / noquota / quota / usrquota
These options are accepted but ignored.
nouid32
Disables 32-bit UIDs and GIDs. This is for inter
operability with older kernels which only store and
expect 16-bit values.
Mount options for ext3
The `ext3' file system is version of the ext2 file system
which has been enhanced with journalling. It supports the
same options as ext2 as well as the following additions:
journal=update
Update the ext3 file system's journal to the cur
rent format.
journal=inum
When a journal already exists, this option is
ignored. Otherwise, it specifies the number of the
inode which will represent the ext3 file system's
overwriting the old contents of the file whose
inode number is inum.
noload Do not load the ext3 file system's journal on
mounting.
data=journal / data=ordered / data=writeback
Specifies the journalling mode for file data.
Metadata is always journaled.
journal
All data is committed into the journal prior
to being written into the main file system.
ordered
This is the default mode. All data is
forced directly out to the main file system
prior to its metadata being committed to the
journal.
writeback
Data ordering is not preserved - data may be
written into the main file system after its
metadata has been committed to the journal.
This is rumoured to be the highest-through
put option. It guarantees internal file
system integrity, however it can allow old
data to appear in files after a crash and
journal recovery.
Mount options for fat
(Note: fat is not a separate filesystem, but a common part
of the msdos, umsdos and vfat filesystems.)
blocksize=512 / blocksize=1024 / blocksize=2048
Set blocksize (default 512).
uid=value and gid=value
Set the owner and group of all files. (Default: the
uid and gid of the current process.)
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.
check=value
Three different levels of pickyness can be chosen:
r[elaxed]
Upper and lower case are accepted and equiv
alent, long name parts are truncated (e.g.
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.)
codepage=value
Sets the codepage for converting to shortname char
acters on FAT and VFAT filesystems. By default,
codepage 437 is used.
conv=b[inary] / conv=t[ext] / conv=a[uto]
The fat file system can perform CRLF<-->NL (MS-DOS
text format to UNIX text format) conversion in the
kernel. The following conversion modes are avail
able:
binary no translation is performed. This is the
default.
text CRLF<-->NL translation is performed on all
files.
auto CRLF<-->NL translation is performed on all
files that don't have a "well-known binary"
extension. The list of known extensions can
be found at the beginning of fs/fat/misc.c
(as of 2.0, the list is: exe, com, bin, app,
sys, drv, ovl, ovr, obj, lib, dll, pif, arc,
zip, lha, lzh, zoo, tar, z, arj, tz, taz,
tzp, tpz, gz, tgz, deb, gif, bmp, tif, gl,
jpg, pcx, tfm, vf, gf, pk, pxl, dvi).
Programs that do computed lseeks won't like in-ker
nel text conversion. Several people have had their
data ruined by this translation. Beware!
For file systems mounted in binary mode, a conver
sion tool (fromdos/todos) is available.
cvf_format=module
Forces the driver to use the CVF (Compressed Volume
File) module cvf_module instead of auto-detection.
If the kernel supports kmod, the cvf_format=xxx
cvf_option=option
Option passed to the CVF module.
debug Turn on the debug flag. A version string and a
list of file system parameters will be printed
(these data are also printed if the parameters
appear to be inconsistent).
fat=12 / fat=16 / fat=32
Specify a 12, 16 or 32 bit fat. This overrides the
automatic FAT type detection routine. Use with
caution!
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.
quiet Turn on the quiet flag. Attempts to chown or chmod
files do not return errors, although they fail. Use
with caution!
sys_immutable, showexec, dots, nodots, dotsOK=[yes|no]
Various misguided attempts to force Unix or DOS
conventions onto a FAT file system.
Mount options for hpfs
uid=value and gid=value
Set the owner and group of all files. (Default: the
uid and gid of the current process.)
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.
case=lower / case=asis
Convert all files names to lower case, or leave
them. (Default: case=lower.)
conv=binary / conv=text / conv=auto
For conv=text, delete some random CRs (in particu
lar, all followed by NL) when reading a file. For
conv=auto, choose more or less at random between
conv=binary and conv=text. For conv=binary, just
read what is in the file. This is the default.
nocheck
Do not abort mounting when certain consistency
checks fail.
Normal iso9660 filenames appear in a 8.3 format (i.e.,
DOS-like restrictions on filename length), and in addition
all characters are in upper case. Also there is no field
for file ownership, protection, number of links, provision
for block/character devices, etc.
Rock Ridge is an extension to iso9660 that provides all of
these unix like features. Basically there are extensions
to each directory record that supply all of the additional
information, and when Rock Ridge is in use, the filesystem
is indistinguishable from a normal UNIX file system
(except that it is read-only, of course).
norock Disable the use of Rock Ridge extensions, even if
available. Cf. map.
nojoliet
Disable the use of Microsoft Joliet extensions,
even if available. Cf. map.
check=r[elaxed] / check=s[trict]
With check=relaxed, a filename is first converted
to lower case before doing the lookup. This is
probably only meaningful together with norock and
map=normal. (Default: check=strict.)
uid=value and gid=value
Give all files in the file system the indicated
user or group id, possibly overriding the informa
tion found in the Rock Ridge extensions. (Default:
uid=0,gid=0.)
map=n[ormal] / map=o[ff] / map=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.
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.
block=[512|1024|2048]
Set the block size to the indicated value.
(Default: block=1024.)
(Default: conv=binary.) Since Linux 1.3.54 this
option has no effect anymore. (And non-binary set
tings used to be very dangerous, possibly leading
to silent data corruption.)
cruft If the high byte of the file length contains other
garbage, set this mount option to ignore the high
order bits of the file length. This implies that a
file cannot be larger than 16MB. The `cruft'
option is set automatically if the entire CDROM has
a weird size (negative, or more than 800MB). It is
also set when volume sequence numbers other than 0
or 1 are seen.
session=x
Select number of session on multisession CD. (Since
2.3.4.)
sbsector=xxx
Session begins from sector xxx. (Since 2.3.4.)
Mount options for minix
None.
Mount options for msdos
See mount options for fat. If the msdos file system
detects an inconsistency, it reports an error and sets the
file system read-only. The file system can be made write
able again by remounting it.
Mount options for ncp
Just like nfs, the ncp implementation expects a binary
argument (a struct ncp_mount_data) to the mount system
call. This argument is constructed by ncpmount(8) and the
current version of mount (2.6h) does not know anything
about ncp.
Mount options for nfs
Instead of a textual option string, parsed by the kernel,
the nfs file system expects a binary argument of type
struct nfs_mount_data. The program mount itself parses
the following options of the form `tag=value', and puts
them in the structure mentioned: rsize=n, wsize=n,
timeo=n, retrans=n, acregmin=n, acregmax=n, acdirmin=n,
acdirmax=n, actimeo=n, retry=n, port=n, mountport=n, moun
thost=name, mountprog=n, mountvers=n, nfsprog=n,
nfsvers=n, namlen=n. The option addr=n is accepted but
ignored. Also the following Boolean options, possibly
preceded by no are recognized: bg, fg, soft, hard, intr,
Especially useful options include
rsize=8192,wsize=8192
This will make your nfs connection faster than with
the default buffer size of 4096. (NFSv2 does not
work with larger values of rsize and wsize.)
hard The program accessing a file on a NFS mounted file
system will hang when the server crashes. The pro
cess cannot be interrupted or killed unless you
also specify intr. When the NFS server is back
online the program will continue undisturbed from
where it was. This is probably what you want.
soft This option allows the kernel to time out if the
nfs server is not responding for some time. The
time can be specified with timeo=time. This option
might be useful if your nfs server sometimes
doesn't respond or will be rebooted while some pro
cess tries to get a file from the server. Usually
it just causes lots of trouble.
nolock Do not use locking. Do not start lockd.
Mount options for ntfs
iocharset=name
Character set to use when returning file names.
Unlike VFAT, NTFS suppresses names that contain
unconvertible characters.
utf8 Use UTF-8 for converting file names.
uni_xlate=[0|1|2]
For 0 (or `no' or `false') or 1 (or `yes' or
`true'): use the VFAT-style encoding for file names
outside the current character set. A value of 2
will disable the encoding with ":".
posix=[0|1]
If enabled (posix=1), the file system distinguishes
between upper and lower case. The 8.3 alias names
are presented as hard links instead of being sup
pressed.
uid=value, gid=value and umask=value
Set the file permission on the filesystem. By
default, the files are owned by root and not read
able by somebody else.
uid=value and gid=value
These options are recognized, but have no effect as
far as I can see.
Mount options for reiserfs
The reiserfs mount options are more fully described at
http://www.namesys.com/mount-options.html
conv Instructs version 3.6 reiserfs software to mount a
version 3.5 file system, using the 3.6 format for
newly created objects. This file system will no
longer be compatible with reiserfs 3.5 tools.
hash=rupasov / hash=tea / hash=r5 / hash=detect
Choose which hash function reiserfs will use to
find files within directories.
rupasov
A hash invented by Yury Yu. Rupasov. It is
fast and preserves locality, mapping lexico
graphically close file names to close hash
values. This option should not be used, as
it causes a high probability of hash colli
sions.
tea A Davis-Meyer function implemented by Jeremy
Fitzhardinge. It uses hash permuting bits
in the name. It gets high randomness and,
therefore, low probability of hash colli
sions at come CPU cost. This may be used if
EHASHCOLLISION errors are experienced with
the r5 hash.
r5 A modified version of the rupasov hash. It
is used by default and is the best choice
unles the file system has huge directories
and unusual file-name patterns.
detect Instructs mount to detect which hash func
tion is in use by examining the file system
being mounted, and to write this informa
tion into the reiserfs superblock. This is
only useful on the first mount of an old
format file system.
hashed_relocation
Tunes the block allocator. This may provide some
performance improvements in some situations.
noborder
Disable the border allocator algorithm invented by
Yury Yu. Rupasov This may provide performance
nolog Disable journalling. This will provide slight per
formance improvements in some situations at the
cost of losing reiserfs's fast recovery from
crashes. Even with this option turned on, reiserfs
still performs all journalling operations, save for
actual writes into its journalling area. Implemen
tation of nolog is a work in progress.
notail By default, reiserfs stores small files and `file
tails' directly into its tree. This confuses some
utilities such as LILO(8). This option is used to
disable packing of files into the tree.
no_unhashed_relocation
Tunes the block allocator. This may provide perfor
mance improvements in some situations.
replayonly
Replay the transactions which are in the journal,
but do not actually mount the file system. Mainly
used by reiserfsck.
resize=nblocks
A remount option which permits online expansion of
reiserfs partitions. Instructs reiserfs to assume
that the device has blocks. This option is
designed for use with devices which are under logi
cal volume management.
Mount options for romfs
None.
Mount options for smbfs
Just like nfs, the smb implementation expects a binary
argument (a struct smb_mount_data) to the mount system
call. This argument is constructed by smbmount(8) and the
current version of mount (2.9w) does not know anything
about smb.
Mount options for sysv
None.
Mount options for udf
gid= Set the default group.
umask= Set the default umask.
uid= Set the default user.
undelete
Show deleted files in lists.
strict Set strict conformance (unused).
utf8 (unused).
iocharset
(unused).
bs= Set the block size. (May not work unless 2048.)
novrs Skip volume sequence recognition.
session=
Set the CDROM session counting from 0. Default:
last session.
anchor=
Override standard anchor location. Default: 256.
volume=
Override the VolumeDesc location. (unused)
partition=
Override the PartitionDesc location. (unused)
lastblock=
Set the last block of the filesystem.
fileset=
Override the fileset block location. (unused)
rootdir=
Override the root directory location. (unused)
Mount options for ufs
ufstype=value
UFS is a file system widely used in different oper
ating 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:
old Old format of ufs, this is the default, read
only.
44bsd For filesystems created by a BSD-like system
(NetBSD,FreeBSD,OpenBSD).
on Sparc.
sunx86 For filesystems created by Solaris on x86.
nextstep
For filesystems created by NeXTStep (on NeXT
station) (currently read only).
nextstep-cd
For NextStep CDROMs (block_size == 2048),
read-only.
openstep
For filesystems created by OpenStep (cur
rently read only).
onerror=value
Set behaviour on error:
panic If an error is encountered, cause a kernel
panic.
[lock|umount|repair]
These mount options don't do anything at
present; when an error is encountered only a
console message is printed.
Mount options for umsdos
See mount options for msdos. The dotsOK option is explic
itly killed by umsdos.
Mount options for vfat
First of all, the mount options for fat are recognized.
The dotsOK option is explicitly killed by vfat. Further
more, there are
uni_xlate
Translate unhandled Unicode characters to special
escaped sequences. This lets you backup and
restore filenames that are created with any Unicode
characters. Without this option, a '?' is used when
no translation is possible. The escape character is
':' because it is otherwise illegal on the vfat
filesystem. The escape sequence that gets used,
where u is the unicode character, is: ':', (u &
0x3f), ((u>>6) & 0x3f), (u>>12).
posix Allow two files with names that only differ in
case.
First try to make a short name without sequence
number, before trying name~num.ext.
utf8 UTF8 is the filesystem safe 8-bit encoding of Uni
code that is used by the console. It can be be
enabled for the filesystem with this option. If
`uni_xlate' gets set, UTF8 gets disabled.
Mount options for xenix
None.
Mount options for xfs
biosize=size
Sets the preferred buffered I/O size (default size
is 64K). size must be expressed as the logarithm
(base2) of the desired I/O size. Valid values for
this option are 14 through 16, inclusive (i.e. 16K,
32K, and 64K bytes). On machines with a 4K page
size, 13 (8K bytes) is also a valid size. The pre
ferred buffered I/O size can also be altered on an
individual file basis using the ioctl(2) system
call.
dmapi / xdsm
Enable the DMAPI (Data Management API) event call
outs.
logbufs=value
Set the number of in-memory log buffers. Valid
numbers range from 2-8 inclusive. The default
value is 8 buffers for filesystems with a blocksize
of 64K, 4 buffers for filesystems with a blocksize
of 32K, 3 buffers for filesystems with a blocksize
of 16K, and 2 buffers for all other configurations.
Increasing the number of buffers may increase per
formance on some workloads at the cost of the mem
ory used for the additional log buffers and their
associated control structures.
logbsize=value
Set the size of each in-memory log buffer. Valid
sizes are 16384 (16K) and 32768 (32K). The default
value for machines with more than 32MB of memory is
32768, machines with less memory use 16384 by
default.
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,
section or contained within it. Refer to xfs(5).
noalign
Data allocations will not be aligned at stripe unit
boundaries.
noatime
Access timestamps are not updated when a file is
read.
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 directo
ries may not be accessible because of this.
Filesystems mounted norecovery must be mounted
read-only or the mount will fail.
osyncisdsync
Make writes to files opened with the O_SYNC flag
set behave as if the O_DSYNC flag had been used
instead. This can result in better performance
without compromising data safety. However if this
option is in effect, timestamp updates from O_SYNC
writes can be lost if the system crashes.
quota / usrquota / uqnoenforce
User disk quota accounting enabled, and limits
(optionally) enforced.
grpquota / gqnoenforce
Group disk quota accounting enabled and limits
(optionally) enforced.
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.
None. Although nothing is wrong with xiafs, it is not used
much, and is not maintained. Probably one shouldn't use
it. Since Linux version 2.1.21 xiafs is no longer part of
the kernel source.
THE LOOP DEVICE
One further possible type is a mount via the loop device.
For example, the command
mount /tmp/fdimage /mnt -t msdos -o loop=/dev/loop3,blocksize=1024
will set up the loop device /dev/loop3 to correspond to
the file /tmp/fdimage, and then mount this device on /mnt.
This type of mount knows about three options, namely loop,
offset and encryption, that are really options to los
etup(8). If no explicit loop device is mentioned (but
just an option `-o loop' is given), then mount will try to
find some unused loop device and use that. If you are not
so unwise as to make /etc/mtab a symbolic link to
/proc/mounts then any loop device allocated by mount will
be freed by umount. You can also free a loop device by
hand, using `losetup -d', see losetup(8).
FILES
/etc/fstab file system table
/etc/mtab table of mounted file systems
/etc/mtab~ lock file
/etc/mtab.tmp temporary file
SEE ALSO
mount(2), umount(2), fstab(5), umount(8), swapon(8),
nfs(5), xfs(5), e2label(8), xfs_admin(8), mountd(8),
nfsd(8), mke2fs(8), tune2fs(8), losetup(8)
BUGS
It is possible for a corrupted file system to cause a
crash.
Some Linux file systems don't support -o sync (the ext2
and ext3 file systems do support synchronous updates (a la
BSD) when mounted with the sync option).
The -o remount may not be able to change mount parameters
(all ext2fs-specific parameters, except sb, are changeable
with a remount, for example, but you can't change gid or
umask for the fatfs).
HISTORY
A mount command existed in Version 5 AT&T UNIX.
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