mdmfs(8)
NAME
- mdmfs, mount_mfs - configure and mount an in-memory file
- system using the
md(4) driver
SYNOPSIS
mdmfs [-DLlMNSUX] [-a maxcontig] [-b block-size] [-c cylinders] [-d rotdelay] [-e maxbpg] [-F file] [-f frag-size] [-i bytes] [-m percent-free] [-n rotational-positions] [-O optimization] [-o mount-options] [-p permissions] [-s size] [-v version] [-w user:group] md-device mount-point mdmfs -C [-lNU] [-a maxcontig] [-b block-size] [-c cylinders] [-d rotdelay] [-e maxbpg] [-F file] [-f frag-size] [-i bytes] [-m percent-free] [-n rotational-positions] [-O optimization] [-o mount-options] [-s size] [-v version] md-device mount-point
DESCRIPTION
- The mdmfs utility is designed to be a work-alike and look
- alike of the
deprecated mount_mfs(8). The end result is essentially the - same, but is
accomplished in a completely different way. The mdmfs util - ity configures
an md(4) disk using mdconfig(8), puts a UFS file system on - it using
newfs(8), and mounts it using mount(8). All the command - line options are
passed to the appropriate program at the appropriate stage - in order to
achieve the desired effect. - By default, mdmfs creates a swap-based (MD_SWAP) disk with
- soft-updates
enabled and mounts it on mount-point. It uses the md(4) de - vice specified
by md-device. If md-device is `md' (no unit number), it - will use md(4)'s
auto-unit feature to automatically select an unused device. - Unless otherwise specified with one of the options below, it uses the
- default arguments to all the helper programs.
- The following options are available. Where possible, the
- option letter
matches the one used by mount_mfs(8) for the same thing. - -a maxcontig
- Specify the maximum number of contiguous blocks that
- will be laid
out before forcing a rotational delay (see the -d - option).
- -b block-size
- The block size of the file system, in bytes.
- -C Enable full compatibility mode with mount_mfs(8).
- See the
- COMPATIBILITY section for more information.
- -c cylinders
- The number of cylinders per cylinder group in the
- file system.
- -D If not using auto-unit, do not run mdconfig(8) to
- try to detach
- the unit before attaching it.
- -d rotdelay
- Specify the minimum time in milliseconds required to
- initiate
another disk transfer on the same cylinder. Modern - disks with
read/write-behind achieve higher performance without - this feature, so it is best to leave it at 0 milliseconds.
- -e maxbpg
- Indicate the maximum number of blocks any single
- file can allocate out of a cylinder group before it is forced to
- begin allocating blocks from another cylinder group.
- -F file
- Create a vnode-backed (MD_VNODE) memory disk backed
- by file.
- -f frag-size
- The fragment size of the file system in bytes.
- -i bytes
- Number of bytes per inode.
- -l Enable multilabel MAC on the new file system.
- -L Show the output of the helper programs. By default,
- it is sent
- to /dev/null.
- -M Create a malloc(9) backed disk (MD_MALLOC) instead
- of a swap
- backed disk.
- -m percent-free
- The percentage of space reserved for the superuser.
- -N Do not actually run the helper programs. This is
- most useful in
- conjunction with -X.
- -n rotational-positions
- The default number of rotational positions to dis
- tinguish.
- -O optimization
- Select the optimization preference; valid choices
- are space and
time, which will optimize for minimum space fragmen - tation and
minimum time spent allocating blocks, respectively. - -o mount-options
- Specify the mount options with which to mount the
- file system.
See mount(8) for more information. - -p permissions
- Set the file (directory) permissions of the mount
- point
mount-point to permissions. The permissions argu - ment can be in
any of the mode formats recognized by chmod(1). If - symbolic permissions are specified, the operation characters
- ``+'' and ``-''
are interpreted relative to the initial permissions - of ``a=rwx''.
- -S Do not enable soft-updates on the file system.
- -s size
- Specify the size of the disk to create. This only
- makes sense if
-F is not specified. That is, this will work for - the default
swap-backed (MD_SWAP) disks, and the optional (-M) - malloc(9)
backed disks (MD_MALLOC). - -U Enable soft-updates on the file system. This is the
- default,
- even in compatibility mode, and is accepted only for
- compatibility. It is only really useful to negate the -S
- flag, should such
a need occur. - -v version
- Specify the UFS version number for use on the file
- system; it may
be either 1 or 2. The default is derived from the - default of the
newfs(8) command. - -w user:group
- Set the owner and group to user and group, respec
- tively. The
arguments have the same semantics as with chown(8), - but specifying just a user or just a group is not supported.
- -X Print what command will be run before running it,
- and other
- assorted debugging information.
- The -F and -s options are passed to mdconfig(8) as -f and
- -s, respectively. The -a, -b, -c, -d, -e, -f, -i, -m and -n options
- are passed to
newfs(8) with the same letter; the -O option is passed to - newfs(8) as -o.
The -o option is passed to mount(8) with the same letter. - See the programs that the options are passed to for more information on
- their semantics.
EXAMPLES
- Create and mount a 32 megabyte swap-backed file system on
- /tmp:
mdmfs -s 32m md /tmp- The same file system created as an entry in /etc/fstab:
md /tmp mfs rw,-s32m 2 0- Create and mount a 16 megabyte malloc-backed file system on
- /tmp using
the /dev/md1 device; furthermore, do not use soft-updates on - it and mount
it async:
mdmfs -M -S -o async -s 16m md1 /tmp
COMPATIBILITY
- The mdmfs utility, while designed to be fully compatible
- with
mount_mfs(8), can be useful by itself. Since mount_mfs(8) - had some silly
defaults, a ``full compatibility'' mode is provided for the - case where
bug-to-bug compatibility is desired. - Full compatibility is enabled with the -C flag, or by start
- ing mdmfs with
the name mount_mfs or mfs (as returned by getprogname(3)). - In this mode,
only the options which would be accepted by mount_mfs(8) are - valid. Furthermore, the following behavior, as done by mount_mfs(8),
- is duplicated:
+o The file mode of mount-point is set to 01777 as if- -p 1777 was
given on the command line.
SEE ALSO
md(4), fstab(5), mdconfig(8), mount(8), newfs(8)
AUTHORS
- Dima Dorfman
- BSD February 26, 2004