f7ca2bbe44
This feature comes from the fact that we rely memory-backed md(4) in our build process heavily. However, if the build goes haywire the allocated resources (i.e. swap and memory-backed md(4)'s) need to be purged. It is extremely useful to have ability to attach arbitrary labels to each of the virtual disks so that they can be identified and GC'ed if neecessary. MFC after: 4 weeks Differential Revision: https://reviews.freebsd.org/D10457
337 lines
8.3 KiB
Groff
337 lines
8.3 KiB
Groff
.\" Copyright (c) 1993 University of Utah.
|
|
.\" Copyright (c) 1980, 1989, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\" Copyright (c) 2000
|
|
.\" Poul-Henning Kamp All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to Berkeley by
|
|
.\" the Systems Programming Group of the University of Utah Computer
|
|
.\" Science Department.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)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 August 28, 2017
|
|
.Dt MDCONFIG 8
|
|
.Os
|
|
.Sh NAME
|
|
.Nm mdconfig
|
|
.Nd create and control memory disks
|
|
.Sh SYNOPSIS
|
|
.Nm
|
|
.Fl a
|
|
.Fl t Ar type
|
|
.Op Fl n
|
|
.Oo Fl o Oo Cm no Oc Ns Ar option Oc ...
|
|
.Op Fl f Ar file
|
|
.Op Fl s Ar size
|
|
.Op Fl S Ar sectorsize
|
|
.Op Fl u Ar unit
|
|
.Op Fl x Ar sectors/track
|
|
.Op Fl y Ar heads/cylinder
|
|
.Op Fl L Ar label
|
|
.Nm
|
|
.Fl d
|
|
.Fl u Ar unit
|
|
.Op Fl o Oo Cm no Oc Ns Ar force
|
|
.Nm
|
|
.Fl r
|
|
.Fl u Ar unit
|
|
.Fl s Ar size
|
|
.Op Fl o Oo Cm no Oc Ns Ar force
|
|
.Nm
|
|
.Fl l
|
|
.Op Fl n
|
|
.Op Fl v
|
|
.Op Fl f Ar file
|
|
.Op Fl u Ar unit
|
|
.Nm
|
|
.Ar file
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
utility creates and controls
|
|
.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.
|
|
If the
|
|
.Fl u Ar unit
|
|
option is not provided, the newly created device name will be printed on stdout.
|
|
.It Fl d
|
|
Detach a memory disk from the system and release all resources.
|
|
.It Fl r
|
|
Resize a memory disk.
|
|
.It Fl t Ar type
|
|
Select the type of the memory disk.
|
|
.Bl -tag -width "malloc"
|
|
.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.
|
|
If the
|
|
.Fl o Cm reserve
|
|
option is not set, creating and filling a large
|
|
malloc-backed memory disk is a very easy way to
|
|
panic the system.
|
|
.It Cm vnode
|
|
A file specified with
|
|
.Fl f Ar file
|
|
becomes the backing store for this memory disk.
|
|
.It Cm swap
|
|
Storage for this type of memory disk is allocated from buffer
|
|
memory.
|
|
Pages get pushed out to swap when the system is under memory
|
|
pressure, otherwise they stay in the operating memory.
|
|
Using
|
|
.Cm swap
|
|
backing is generally preferred instead of using
|
|
.Cm malloc
|
|
backing.
|
|
.It Cm null
|
|
Bitsink; all writes do nothing, all reads return zeroes.
|
|
.El
|
|
.It Fl f Ar file
|
|
Filename to use for the vnode type memory disk.
|
|
The
|
|
.Fl a
|
|
and
|
|
.Fl t Ar vnode
|
|
options are implied if not specified.
|
|
.It Fl l
|
|
List configured devices.
|
|
If given with
|
|
.Fl u ,
|
|
display details about that particular device.
|
|
If given with
|
|
.Fl f Ar file ,
|
|
display
|
|
.Xr md 4
|
|
device names of which
|
|
.Ar file
|
|
is used as the backing store.
|
|
If both of
|
|
.Fl u
|
|
and
|
|
.Fl f
|
|
options are specified,
|
|
display devices which match the two conditions.
|
|
If the
|
|
.Fl v
|
|
option is specified, show all details.
|
|
.It Fl n
|
|
When printing
|
|
.Xr md 4
|
|
device names, print only the unit number without the
|
|
.Xr md 4
|
|
prefix.
|
|
.It Fl s Ar size
|
|
Size of the memory disk.
|
|
.Ar Size
|
|
is the number of 512 byte sectors unless suffixed with a
|
|
.Cm b , k , m , g , t ,
|
|
or
|
|
.Cm p
|
|
which
|
|
denotes byte, kilobyte, megabyte, gigabyte, terabyte and petabyte respectively.
|
|
When used without the
|
|
.Fl r
|
|
option, the
|
|
.Fl a
|
|
and
|
|
.Fl t Ar swap
|
|
options are implied if not specified.
|
|
.It Fl S Ar sectorsize
|
|
Sectorsize to use for the memory disk, in bytes.
|
|
.It Fl x Ar sectors/track
|
|
See the description of the
|
|
.Fl y
|
|
option below.
|
|
.It Fl y Ar heads/cylinder
|
|
For
|
|
.Cm malloc
|
|
or
|
|
.Cm vnode
|
|
backed devices, the
|
|
.Fl x
|
|
and
|
|
.Fl y
|
|
options can be used to specify a synthetic geometry.
|
|
This is useful for constructing bootable images for later download to
|
|
other devices.
|
|
.It Fl L Ar label
|
|
Associate a label (arbitrary string) with the new memory disk.
|
|
The label can then be inspected with
|
|
.Bd -literal -offset indent
|
|
.Nm Fl l v
|
|
.Ed
|
|
.It Fl o Oo Cm no Oc Ns Ar option
|
|
Set or reset options.
|
|
.Bl -tag -width indent
|
|
.It Oo Cm no Oc Ns Cm async
|
|
For
|
|
.Cm vnode
|
|
backed devices: avoid
|
|
.Dv IO_SYNC
|
|
for increased performance but
|
|
at the risk of deadlocking the entire kernel.
|
|
.It Oo Cm no Oc Ns Cm reserve
|
|
Allocate and reserve all needed storage from the start, rather than as needed.
|
|
.It Oo Cm no Oc Ns Cm cluster
|
|
Enable clustering on this disk.
|
|
.It Oo Cm no Oc Ns Cm compress
|
|
Enable/disable compression features to reduce memory usage.
|
|
.It Oo Cm no Oc Ns Cm force
|
|
Disable/enable extra sanity checks to prevent the user from doing something
|
|
that might adversely affect the system.
|
|
This can be used with the
|
|
.Fl d
|
|
flag to forcibly destroy an
|
|
.Xr md 4
|
|
disk that is still in use.
|
|
.It Oo Cm no Oc Ns Cm readonly
|
|
Enable/disable readonly mode.
|
|
.It Oo Cm no Oc Ns Cm verify
|
|
For
|
|
.Cm vnode
|
|
backed devices: enable/disable requesting verification of the
|
|
file used for backing store.
|
|
The type of verification depends on which security features are available.
|
|
One example of verification is testing file integrity with
|
|
checksums or cryptographic signatures.
|
|
.El
|
|
.It Fl u Ar unit
|
|
Request a specific unit number or device name for the
|
|
.Xr md 4
|
|
device instead of automatic allocation.
|
|
If a device name is specified, it must be start with
|
|
.Dq md
|
|
followed by the unit number.
|
|
.El
|
|
.Pp
|
|
The last form,
|
|
.Nm
|
|
.Ar file ,
|
|
is provided for convenience as an abbreviation of
|
|
.Nm
|
|
.Fl a
|
|
.Fl t Ar vnode
|
|
.Fl f Ar file .
|
|
.Sh EXAMPLES
|
|
Create a disk with
|
|
.Pa /tmp/boot.flp
|
|
as backing storage.
|
|
The name of the allocated unit will be printed on stdout, such as
|
|
.Dq Li md0 :
|
|
.Bd -literal -offset indent
|
|
mdconfig /tmp/boot.flp
|
|
.Ed
|
|
.Pp
|
|
Create a 1 gigabyte swap backed memory disk named
|
|
.Dq Li md3 :
|
|
.Bd -literal -offset indent
|
|
mdconfig -s 1g -u md3
|
|
.Ed
|
|
.Pp
|
|
Detach and free all resources used by
|
|
.Pa /dev/md3 :
|
|
.Bd -literal -offset indent
|
|
mdconfig -du md3
|
|
.Ed
|
|
.Pp
|
|
Show detailed information on current memory disks:
|
|
.Bd -literal -offset indent
|
|
mdconfig -lv
|
|
.Ed
|
|
.Pp
|
|
Resize the
|
|
.Dq Li md3
|
|
memory disk to 2 gigabytes:
|
|
.Bd -literal -offset indent
|
|
mdconfig -rs 2g -u md3
|
|
.Ed
|
|
.Pp
|
|
Create a 1 gigabyte swap backed disk, initialize an
|
|
.Xr ffs 7
|
|
file system on it, and mount it on
|
|
.Pa /tmp :
|
|
.Bd -literal -offset indent
|
|
mdconfig -s 1g -u md10
|
|
newfs -U /dev/md10
|
|
mount /dev/md10 /tmp
|
|
chmod 1777 /tmp
|
|
.Ed
|
|
.Pp
|
|
Create a memory disk out of an ISO 9660 CD image file,
|
|
using the first available
|
|
.Xr md 4
|
|
device, and then mount it:
|
|
.Bd -literal -offset indent
|
|
mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt
|
|
.Ed
|
|
.Pp
|
|
Create a file-backed device from a hard disk image that begins
|
|
with 512K of raw header information.
|
|
.Xr gnop 8
|
|
is used to skip over the header information, positioning
|
|
.Pa md1.nop
|
|
to the start of the filesystem in the image.
|
|
.Bd -literal -offset indent
|
|
mdconfig -u md1 -f diskimage.img
|
|
gnop create -o 512K md1
|
|
mount /dev/md1.nop /mnt
|
|
.Ed
|
|
.Sh SEE ALSO
|
|
.Xr open 2 ,
|
|
.Xr md 4 ,
|
|
.Xr ffs 7 ,
|
|
.Xr gpart 8 ,
|
|
.Xr mdmfs 8 ,
|
|
.Xr malloc 9
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
utility first appeared in
|
|
.Fx 5.0
|
|
as a cleaner replacement for the
|
|
.Xr vn 4
|
|
and
|
|
.Xr vnconfig 8
|
|
combo.
|
|
.Sh AUTHORS
|
|
The
|
|
.Nm
|
|
utility was written by
|
|
.An Poul-Henning Kamp Aq Mt phk@FreeBSD.org .
|