\"      $NetBSD: vnconfig.8,v 1.51 2025/02/10 22:46:21 gutteridge Exp $
\"
\" Copyright (c) 1997 The NetBSD Foundation, Inc.
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\" This code is derived from software contributed to The NetBSD Foundation
\" by Jason R. Thorpe.
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\" modification, are permitted provided that the following conditions
\" are met:
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\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION OR CONTRIBUTORS
\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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\" 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
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\" Copyright (c) 1993 University of Utah.
\" Copyright (c) 1980, 1989, 1991, 1993
\"      The Regents of the University of California.  All rights reserved.
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\" This code is derived from software contributed to Berkeley by
\" the Systems Programming Group of the University of Utah Computer
\" Science Department.
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\" Redistribution and use in source and binary forms, with or without
\" modification, are permitted provided that the following conditions
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\"    notice, this list of conditions and the following disclaimer.
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\" 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
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\"
\"      @(#)vnconfig.8  8.1 (Berkeley) 6/5/93
\"
Dd October 20, 2023
Dt VNDCONFIG 8
Os
Sh NAME
Nm vndconfig
Nd configure vnode disks
Sh SYNOPSIS
Nm
\" Fcf:lm:rt:uvz
Op Fl cirvz
Op Fl f Ar disktab
Op Fl t Ar typename
Ar vnode_disk
Ar regular_file
Op Ar geomspec
Nm
Fl u
Op Fl Fv
Ar vnode_disk
Nm
Fl l
Op Fl m Ar min
Op Ar vnode_disk ...
Sh DESCRIPTION
The
Nm
command configures vnode pseudo disk devices.
It will associate the vnode disk
Ar vnode_disk
with the regular file
Ar regular_file
allowing the latter to be accessed as though it were a disk.
Hence a regular file within the filesystem can be used for swapping
or can contain a filesystem that is mounted in the name space.
The
Ar vnode_disk
is a special file of raw partition or name of vnode disk like
Pa vnd0 .
Pp
By default, accesses to the file bypass normal mechanisms and thus
do not read from or fill the filesystem cache.
Because the typical approach is to access the file only via
Xr vnd 4 ,
or at least to have regular accesses and
Xr vnd 4
accesses separated in time, this is generally not problematic.
This bypassing behavior results in not updating the modification
timestamp of the file.
Also, file contents read through the filesystem (and thus the
filesystem's caching layer) may not be the contents written via this
interface, so caution is in order for backups.
The
Fl i
option may be useful if it is necessary to avoid inconsistent caching.
Pp
Options indicate an action to be performed:
Bl -tag -width indent
It Fl c
Configures the device.
If successful, references to
Ar vnode_disk
will access the contents of
Ar regular_file .
Pp
If
Ar geomspec
is specified, the vnode device will emulate the specified disk geometry.
The format of the
Ar geomspec
argument is:
Bd -ragged -offset indent
Sm off
Xo Ar secsize Li / Ar nsectors Li /
Ar ntracks Li / Ar ncylinders Xc
Sm on
Ed
Pp
If geometry is not specified, the kernel will choose a default based on 1MB
cylinders.
Ar secsize
is the number of bytes per sector.
It must be a power of two, and at least 512.
Ar nsectors
is the number of sectors per track.
Ar ntracks
is the number of tracks per cylinder.
Ar ncylinders
is the number of cylinders in the device.
It Fl F
Force unconfiguration if the device is in use.
Does not imply
Fl u .
It Fl f Ar disktab
Specifies that the
Fl t
option should look up in
Ar disktab
instead of in
Pa /etc/disktab .
It Fl i
Configure the device to use regular file I/O even when direct I/O using
bmap/strategy would be possible.
It Fl l
List the vnd devices and indicate which ones are in use.
If one or more specific
Ar vnode_disks
are given, then only those will be described.
It Fl m Ar min
Together with
Fl l
and if no specific devices are given,
causes at least
Ar min
devices to be listed.
The default for
Ar min
is 4,
but all vnd devices up to (and sometimes just beyond)
the highest numbered vnd device configured since
the system last booted will be listed.
If
Ar min
is set to 0,
then only vnd devices currently in use will be shown.
It Fl r
Configure the device as read-only.
It Fl t Ar typename
If configuring the device, look up
Ar typename
in
Pa /etc/disktab
and use the geometry specified in the entry.
This option and the
Ar geomspec
argument are mutually exclusive.
It Fl u
Unconfigures the device.
It Fl v
Print messages to stdout describing actions taken.
It Fl z
Assume that
Ar regular_file
is a compressed disk image in cloop2 format, and configure it
read-only.
See the
Xr vndcompress 1
manpage on how to create such an image.
El
Pp
If no action option
Op Fl clu
is given,
Fl c
is assumed.
Sh FILES
Bl -tag -width /etc/disktab -compact
It Pa /dev/rvnd??
It Pa /dev/vnd??
It Pa /etc/disktab
El
Sh EXIT STATUS
Nm
will exit with status 0 if the operation requested
completed successfully,
or 1 otherwise.
Unsuccessful completion can be caused by unknown or
incorrectly used options;
attempting to configure a vnd that is already configured;
or unconfigure one that is not, or without
Fl F ,
one which is still in use;
or if devices are specified that do not exist or are not
Xr vnd 4
devices, giving an improper geometry, etc.
Sh EXAMPLES
Dl vndconfig vnd0 /tmp/diskimage
or
Dl vndconfig /dev/rvnd0c /tmp/diskimage
Pp
Configures the vnode disk
Pa vnd0 .
Please note that use of the second form of the command is discouraged because
it requires knowledge of the raw partition which varies between architectures.
For the first form, be aware that there must not be a file
Ar vnd0
in the current directory, or it will be assumed to be the vnd device to
be configured (which will usually fail).
Pp
Dl vndconfig vnd0 /tmp/floppy.img 512/18/2/80
Pp
Configures the vnode disk
Pa vnd0
emulating the geometry of 512 bytes per sector, 18 sectors per track,
2 tracks per cylinder, and 80 cylinders total.
Pp
Dl vndconfig vnd0 /tmp/image.udf 2048/1/1/0
Pp
Configures the vnode disk
Pa vnd0
for an UDF image to be used with
Xr mount_udf 8 .
Pp
Dl vndconfig -t floppy vnd0 /tmp/floppy.img
Pp
Configures the vnode disk
Pa vnd0
using the geometry specified in the
Pa floppy
entry in
Pa /etc/disktab .
Pp
Dl vndconfig -u vnd0
Pp
Unconfigures the
Pa vnd0
device.
Pp
To obtain status on all vnd devices listed in
Pa /dev
(assuming a system where the
Sq d
partition is the whole device
Pq Dv RAW_PART ) ,
use:
Pp
Dl vndconfig -l /dev/vnd*d
Pp
Using
Dl vndconfig -m0 -l /dev/vnd*d
will omit those devices that are not in use, whereas
Dl vndconfig -l
will list all devices known to the kernel (at least 4
without
Fl m )
regardless of what might appear in
Pa /dev
(or elsewhere.)
Sh SEE ALSO
Xr vndcompress 1 ,
Xr opendisk 3 ,
Xr vnd 4 ,
Xr mount 8 ,
Xr swapctl 8 ,
Xr umount 8
Sh HISTORY
The
Nm vnconfig
command appeared in
Nx 1.0 .
It was renamed to
Nm
in
Nx 7.0
for consistency with other similar commands.
(The original name was also retained as an alternative
for backwards compatibility.)

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