sbin/mdmfs/mdmfs.8

    mdmfs.8 revision 153961

 Copyright (c) 2001 Dima Dorfman.
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 $FreeBSD: head/sbin/mdmfs/mdmfs.8 153961 2006-01-02 01:50:30Z dd $

.Dd January 2, 2006
.Dt MDMFS 8
.Os
.Sh NAME
.Nm mdmfs ,
.Nm mount_mfs
.Nd configure and mount an in-memory file system using the
.Xr md 4
driver
.Sh SYNOPSIS
.Nm
.Op Fl DLlMNPSUX
.Op Fl a Ar maxcontig
.Op Fl b Ar block-size
.Op Fl c Ar cylinders
.Op Fl d Ar rotdelay
.Op Fl e Ar maxbpg
.Op Fl F Ar file
.Op Fl f Ar frag-size
.Op Fl i Ar bytes
.Op Fl m Ar percent-free
.Op Fl n Ar rotational-positions
.Op Fl O Ar optimization
.Op Fl o Ar mount-options
.Op Fl p Ar permissions
.Op Fl s Ar size
.Op Fl v Ar version
.Op Fl w Ar user : Ns Ar group
.Ar md-device
.Ar mount-point
.Nm
.Fl C
.Op Fl lNU
.Op Fl a Ar maxcontig
.Op Fl b Ar block-size
.Op Fl c Ar cylinders
.Op Fl d Ar rotdelay
.Op Fl e Ar maxbpg
.Op Fl F Ar file
.Op Fl f Ar frag-size
.Op Fl i Ar bytes
.Op Fl m Ar percent-free
.Op Fl n Ar rotational-positions
.Op Fl O Ar optimization
.Op Fl o Ar mount-options
.Op Fl s Ar size
.Op Fl v Ar version
.Ar md-device
.Ar mount-point
.Sh DESCRIPTION
The
.Nm
utility is designed to be a work-alike and look-alike of the deprecated
.Xr mount_mfs 8 .
The end result is essentially the same,
but is accomplished in a completely different way.
The
.Nm
utility configures an
.Xr md 4
disk using
.Xr mdconfig 8 ,
puts a UFS file system on it using
.Xr newfs 8 ,
and mounts it using
.Xr mount 8 .
All the command line options are passed to the appropriate program
at the appropriate stage in order to achieve the desired effect.
p
By default,
.Nm
creates a swap-based
q Dv MD_SWAP
disk with soft-updates enabled
and mounts it on
.Ar mount-point .
It uses the
.Xr md 4
device specified by
.Ar md-device .
If
.Ar md-device
is
.Ql md
(no unit number),
it will use
.Xr md 4 Ns '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.
p
The following options are available.
Where possible,
the option letter matches the one used by
.Xr mount_mfs 8
for the same thing.
l -tag -width indent t Fl a Ar maxcontig Specify the maximum number of contiguous blocks that will be laid
out before forcing a rotational delay
(see the
.Fl d
option).
t Fl b Ar block-size The block size of the file system, in bytes.
t Fl C Enable full compatibility mode with
.Xr mount_mfs 8 .
See the
.Sx COMPATIBILITY
section for more information.
t Fl c Ar cylinders The number of cylinders per cylinder group in the file system.
t Fl D If not using auto-unit,
do not run
.Xr mdconfig 8
to try to detach the unit before attaching it.
t Fl d Ar 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.
t Fl e Ar 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.
t Fl F Ar file Create a vnode-backed
q Dv MD_VNODE
memory disk backed by
.Ar file .
t Fl f Ar frag-size The fragment size of the file system in bytes.
t Fl i Ar bytes Number of bytes per inode.
t Fl l Enable multilabel MAC on the new file system.
t Fl L Show the output of the helper programs.
By default,
it is sent to
a /dev/null .
t Fl M Create a
.Xr malloc 9
backed disk
q Dv MD_MALLOC
instead of a swap-backed disk.
t Fl m Ar percent-free The percentage of space reserved for the superuser.
t Fl N Do not actually run the helper programs.
This is most useful in conjunction with
.Fl X .
t Fl n Ar rotational-positions The default number of rotational positions to distinguish.
t Fl O Ar optimization Select the optimization preference;
valid choices are
.Cm space
and
.Cm time ,
which will optimize for minimum space fragmentation and
minimum time spent allocating blocks,
respectively.
t Fl o Ar mount-options Specify the mount options with which to mount the file system.
See
.Xr mount 8
for more information.
t Fl P Preserve the existing filesystem;
do not run
.Xr newfs 8 .
This only makes sense if
.Fl F
is specified to create a vnode-backed disk.
t Fl p Ar permissions Set the file (directory) permissions of the mount point
.Ar mount-point
to
.Ar permissions .
The
.Ar permissions
argument can be in any of the mode formats recognized by
.Xr chmod 1 .
If symbolic permissions are specified,
the operation characters
.Dq +
and
.Dq -
are interpreted relative to the initial permissions of
.Dq a=rwx .
t Fl S Do not enable soft-updates on the file system.
t Fl s Ar size Specify the size of the disk to create.
This only makes sense if
.Fl F
is
.Em not
specified.
That is,
this will work for the default swap-backed
q Dv MD_SWAP
disks,
and the optional
q Fl M
.Xr malloc 9
backed disks
q Dv MD_MALLOC .
t Fl 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
.Fl S
flag, should such a need occur.
t Fl v Ar version Specify the UFS version number for use on the file system; it may be
either
.Dv 1
or
.Dv 2 .
The default is derived from the default of the
.Xr newfs 8
command.
t Fl w Ar user : Ns Ar group Set the owner and group to
.Ar user
and
.Ar group ,
respectively.
The arguments have the same semantics as with
.Xr chown 8 ,
but specifying just a
.Ar user
or just a
.Ar group
is not supported.
t Fl X Print what command will be run before running it, and
other assorted debugging information.
.El
p
The
.Fl F
and
.Fl s
options are passed to
.Xr mdconfig 8
as
.Fl f
and
.Fl s ,
respectively.
The
.Fl a , b , c , d , e , f , i , m
and
.Fl n
options are passed to
.Xr newfs 8
with the same letter;
the
.Fl O
option is passed to
.Xr newfs 8
as
.Fl o .
The
.Fl o
option is passed to
.Xr mount 8
with the same letter.
See the programs that the options are passed to for more information
on their semantics.
.Sh EXAMPLES
Create and mount a 32 megabyte swap-backed file system on
a /tmp :
p
.Dl "mdmfs -s 32m md /tmp"
p
The same file system created as an entry in
a /etc/fstab :
p
.Dl "md /tmp mfs rw,-s32m 2 0"
p
Create and mount a 16 megabyte malloc-backed file system on
a /tmp
using the
a /dev/md1
device;
furthermore,
do not use soft-updates on it and mount it
.Cm async :
p
.Dl "mdmfs -M -S -o async -s 16m md1 /tmp"
.Sh COMPATIBILITY
The
.Nm
utility, while designed to be fully compatible with
.Xr mount_mfs 8 ,
can be useful by itself.
Since
.Xr mount_mfs 8
had some silly defaults, a
.Dq full compatibility
mode is provided for the case where bug-to-bug compatibility is desired.
p
Full compatibility is enabled with the
.Fl C
flag,
or by starting
.Nm
with the name
.Li mount_mfs
or
.Li mfs
(as returned by
.Xr getprogname 3 ) .
In this mode, only the options which would be accepted by
.Xr mount_mfs 8
are valid.
Furthermore, the following behavior, as done by
.Xr mount_mfs 8 ,
is duplicated:
l -bullet -offset indent t The file mode of
.Ar mount-point
is set to
.Li 01777
as if
.Fl p Ar 1777
was given on the command line.
.El
.Sh SEE ALSO
.Xr md 4 ,
.Xr fstab 5 ,
.Xr mdconfig 8 ,
.Xr mount 8 ,
.Xr newfs 8
.Sh AUTHORS
.An Dima Dorfman