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MDMFS(8)		  BSD System Manager's Manual		      MDMFS(8)

     mdmfs, mount_mfs — configure and mount an in-memory file system using the
     md(4) driver

     mdmfs [-DLlMNPSUX] [-a maxcontig] [-b block-size]
	   [-c blocks-per-cylinder-group] [-d max-extent-size]
	   [-E path-mdconfig] [-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

     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 utility configures
     an md(4) disk using mdconfig(8), puts a UFS file system on it (unless -P
     was specified) using newfs(8), and mounts it using mount(8).  It can han‐
     dle geom_uzip(4) compressed disk images, as long as the kernel supports
     this GEOM class.  All the command line options are passed to the appro‐
     priate program at the appropriate stage in order to achieve the desired

     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) device 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 oth‐
     erwise specified with one of the options below, it uses the default argu‐
     ments 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 blocks-per-cylinder-group
	     The number of blocks 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 max-extent-size
	     The file system may choose to store large files using extents.
	     This parameter specifies the largest extent size that may be
	     used.  It is presently limited to its default value which is 16
	     times the file system blocksize.

     -E path-mdconfig
	     Use path-mdconfig as a location of the mdconfig(8) utility.

     -e maxbpg
	     Indicate the maximum number of blocks any single file can allo‐
	     cate out of a cylinder group before it is forced to begin allo‐
	     cating 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 distinguish.

     -O optimization
	     Select the optimization preference; valid choices are space and
	     time, which will optimize for minimum space fragmentation 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	     Preserve the existing file system; do not run newfs(8).  This
	     only makes sense if -F is specified to create a vnode-backed

     -p permissions
	     Set the file (directory) permissions of the mount point
	     mount-point to permissions.  The permissions argument can be in
	     any of the mode formats recognized by chmod(1).  If symbolic per‐
	     missions 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, 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, respectively.  The
	     arguments have the same semantics as with chown(8), but specify‐
	     ing 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, respec‐
     tively.  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 pro‐
     grams that the options are passed to for more information on their seman‐

     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

     Create and mount a geom_uzip(4) based compressed disk image:

	   mdmfs -P -F foo.uzip -oro md.uzip /tmp/

     Mount the same image, specifying the /dev/md1 device:

	   mdmfs -P -F foo.uzip -oro md1.uzip /tmp/

     Configure a vnode-backed file system and mount its first partition, using
     automatic device numbering:

	   mdmfs -P -F foo.img mds1a /tmp/

     The mdmfs utility, while designed to be compatible with mount_mfs(8), can
     be useful by itself.  Since mount_mfs(8) had some silly defaults, a
     “compatibility” mode is provided for the case where bug-to-bug compati‐
     bility is desired.

     Compatibility is enabled by starting mdmfs with the name mount_mfs or mfs
     (as returned by getprogname(3)).  In this mode, the following behavior,
     as done by mount_mfs(8), is duplicated:

	   ·   The file mode of mount-point is set by default to 01777 as if
	       -p 1777 was given on the command line.

     md(4), fstab(5), mdconfig(8), mount(8), newfs(8)

     Dima Dorfman

BSD			       February 15, 2007			   BSD

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