home | help 
MDMFS(8)		     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 dep-
     recated mount_mfs(8).  The end result is essentially the same, but  is  ac-
     complished  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 en-
     abled  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 other-
     wise 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 an-
	     other 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 distinguish.

     -O optimization
	     Select the optimization preference; valid	choices  are  space  and
	     time, which will optimize for minimum space fragmentation and mini-
	     mum 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 permissions are speci-
	     fied, 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 oc-
	     cur.

     -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 argu-
	     ments 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 as-
	     sorted 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 compat-
     ibility 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:

	   *   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 5.4			February 26, 2004			MDMFS(8)
home | help