Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
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 [-DLlMNPStUX] [-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

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 (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
     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	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
	     disk.

     -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).

     -t	     Turn on the TRIM enable flag for newfs(8).	 The md(4) device sup-
	     ports the BIO_DELETE command, enabling the	TRIM on	created
	     filesystem	allows return of freed memory to the system pool.

     -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-
     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

     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/

COMPATIBILITY
     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:

	   +o   The file	mode of	mount-point is set by default 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		       September 4, 2011		  FreeBSD 10.1

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

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=mdmfs&sektion=8&manpath=FreeBSD+9.3-RELEASE>

home | help