freebsd/sbin/mdconfig/mdconfig.8

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.\"	Poul-Henning Kamp  All rights reserved.
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.\"     @(#)vnconfig.8	8.1 (Berkeley) 6/5/93
.\" from: src/usr.sbin/vnconfig/vnconfig.8,v 1.19 2000/12/27 15:30:29
.\"
.\" $FreeBSD$
.\"
.Dd December 31, 2000
.Dt MDCONFIG 8
.Os FreeBSD
.Sh NAME
.Nm mdconfig
.Nd configure and enable memory disks
.Sh SYNOPSIS
.Nm
.Fl a
.Fl t Ar type 
.Oo
.Fl o
.Oo Cm no Oc Ns Ar option
.Oc
.Op Fl s Ar size
.Op Fl f Ar file
.Op Fl u Ar unit
.Nm
.Fl d
.Fl u Ar unit
.Nm
.Fl l
.Op Fl u Ar unit
.Sh DESCRIPTION
The
.Nm
command configures and enables 
.Xr md 4
devices.
.Pp
Options indicate an action to be performed:
.Bl -tag -width indent
.It Fl a
Attach a memory disk.
This will configure and attach a memory disk with the
parameters specified and attach it to the system.
.It Fl d
Detach a memory disk from the system and release all resources.
.It Fl t Ar type 
Select the type of the memory disk.
.Bl -tag -width "preload"
.It Cm malloc
Storage for this type of memory disk is allocated with
.Xr malloc 9 .
This limits the size to the malloc bucket limit in the kernel.
.It Cm vnode
A file specified with 
.Fl f Ar file
becomes the backingstore for this memory disk.
.It Cm swap
swapspace is used to back this memory disk.
.El
.It Fl f Ar file
Filename to use for the vnode type memory disk.
.It Fl l
List information about configured
.Xr md 4
devices.  If the
.Fl u
option is used in conjuction with this, the output is limited to
information on the specified device.
.It Fl s Ar size
Size of the memory disk.
.Ar Size
is the number of 512 bytes sectors unless suffixed with a
.Cm k , m ,
or
.Cm g
which
denotes kilobyte, megabyte and gigabyte respectively.
.It Xo
.Fl o Oo Cm no Oc Ns Ar option
.Xc
Set or reset options.
.Bl -tag -width indent
.It Xo
.Oo Cm no Oc Ns Cm reserve
.Xc
Allocate and reserve all needed storage from the start, rather than as needed.
.It Xo
.Oo Cm no Oc Ns Cm cluster
.Xc
Enable clustering on this disk.
.It Xo
.Oo Cm no Oc Ns Cm compress
.Xc
Enable/Disable compression features to reduce memory usage.
.It Xo
.Oo Cm no Oc Ns Cm readonly
.Xc
Enable/Disable readonly mode.
.El
.It Fl u Ar unit
Request a specific unit number for the
.Xr md 4
device instead of automatic allocation.
.El
.Sh EXAMPLES
To create a 4 megabyte
.Xr malloc 9
backed memory disk.
The name of the allocated unit will be output on stdout like
.Dq Li md3 :
.Pp
.Dl mdconfig -a -t malloc -s 4m
.Pp
To create a disk named
.Pa /dev/md4
with
.Pa /tmp/boot.flp
as backing:
.Pp
.Dl mdconfig -a -t vnode -f /tmp/boot.flp -u 4
.Pp
To detach and free all resources used by
.Pa /dev/md4 :
.Pp
.Dl mdconfig -d -u 4
.Pp
To create and mount a 128MByte swap backed filesystem on
.Pa /tmp :
.Bd -literal -offset indent
mdconfig -a -t swap -s 128M -u 10
disklabel -r -w md10 auto
newfs /dev/md10c
tunefs -n enable /dev/md10c
mount /dev/md10c /tmp
chmod 1777 /tmp
.Ed
.Sh SEE ALSO
.Xr md 4 ,
.Xr disklabel 8 ,
.Xr fdisk 8 ,
.Xr malloc 9