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MDMFS(8)		FreeBSD	System Manager's Manual		      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 utility 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) 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	     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 fea-
	     ture, so it is best to leave it at	0 milliseconds.

     -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	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,
	     even in compatibility mode, and is	accepted only for compatibil-
	     ity.  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-
     tics.

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 starting 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.  Fur-
     thermore, 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

FreeBSD	10.1		       February	26, 2004		  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | COMPATIBILITY | SEE ALSO | AUTHORS

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