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[dragonfly.git] / usr.sbin / vnconfig / vnconfig.8
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1.\" Copyright (c) 1993 University of Utah.
2.\" Copyright (c) 1980, 1989, 1991, 1993
3.\" The Regents of the University of California. All rights reserved.
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5.\" This code is derived from software contributed to Berkeley by
6.\" the Systems Programming Group of the University of Utah Computer
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37.\" @(#)vnconfig.8 8.1 (Berkeley) 6/5/93
38.\" $FreeBSD: src/usr.sbin/vnconfig/vnconfig.8,v 1.14.2.8 2003/01/04 22:35:53 keramida Exp $
39.\"
40.Dd July 8, 1993
41.Dt VNCONFIG 8
42.Os
43.Sh NAME
44.Nm vnconfig
45.Nd configure and enable vnode disks
46.Sh SYNOPSIS
47.Nm
48.Op Fl cdeguvTZ
49.Oo Fl s Ar option Ns
50.Op , Ns Ar option Ns Ar ... Oc
51.Oo Fl r Ar option Ns
52.Op , Ns Ar option Ns Ar ... Oc
53.Op Fl S Ar value
54.Ar special_file Op Ar regular_file
55.Op Ar feature
56.Nm
57.Fl a
58.Op Fl cdeguv
59.Op Fl s Ar option
60.Op Fl r Ar option
61.Op Fl f Ar config_file
62.Sh DESCRIPTION
63The
64.Nm
65command configures and enables vnode pseudo disk devices.
66The first form of the command will associate the special file
67.Ar special_file
68with the regular file
69.Ar regular_file
70allowing the latter to be accessed as though it were a disk.
71Hence a regular file within the filesystem can be used for swapping
72or can contain a filesystem that is mounted in the name space. If you
73want to use swap backing store for your device instead of a file, you
74can leave regular_file out and specify the size of the block device
75with the -S option.
76.Pp
77Options indicate an action to be performed:
78.Bl -tag -width indent
79.It Fl a
80Read a command file and performs the
81specified actions for each device/file pair.
82.It Fl c
83Configure the device.
84If successful, references to
85.Ar special_file
86will access the contents of
87.Ar regular_file .
88.It Fl d
89Disable (if possible) the specified feature.
90.It Fl e
91Configure the device and enables any
92.Ar feature
93that was specified.
94If no feature was specified,
95.Fl e
96is the same as
97.Fl c .
98.It Fl f Ar config_file
99Use
100.Ar config_file
101as an alternate config file.
102.It Fl g
103Fiddle global options.
104.It Fl r Ar flag
105Reset
106.Ar flag .
107The list of allowed flags and their meanings are:
108.Bl -tag -width "follow"
109.It Ar labels
110use disk/slice labels.
111.It Ar reserve
112Pre-reserve the blocks underlying the file or swap backing store. Currently only
113works for swap backing store. This option also disables on-the-fly freeing of
114the underlying backing store (for example, when you remove a large file).
115Use this option if you wish to avoid long-term fragmentation of the backing
116store. Also note that when this option is used, the initial contents of the
117backing store may contain garbage rather then zeros. It may even be possible to
118recover the prior contents of a swap-backed VN across a reboot if the VN device
119is configured before any swap is allocated by the system.
120.It Ar follow
121debug flow in the
122.Xr vn 4
123driver.
124.It Ar debug
125debug data in the
126.Xr vn 4
127driver.
128.It Ar io
129debug I/O in the
130.Xr vn 4
131driver.
132.It Ar all
133turn on all flags.
134.It Ar none
135turn off all flags.
136.El
137.It Fl s Ar flag
138Set
139.Ar flag .
140The list of allowed flags and their meanings are the same as for the
141.Fl r
142option.
143.It Fl S Xo
144.Sm off
145.Ar value
146.Es \&{ \&}
147.En Cm k , m , g , t
148.Sm on
149.Xc
150If no regular file is specified, VN will use swap for backing store.
151This option specifies the size of the device. For example, '23m' for
15223 megabytes. The VN device will round the size up to a machine page boundary.
153Filesystems up to 7.9 terabytes are supported. When specified along with
154a regular file, this option overrides the regular file's size insofar as
155VN is concerned.
156.It Fl T
157When a regular file is specified, VN will ftruncate() the file to 0 first.
158Normally you should also specify the -S option to set the size of the file.
159This option also creates the file if it did not previously exist.
160This option is only meaningful if the -S option has been specified.
161.It Fl Z
162When a regular file is specified, VN will zero the contents of the file to
163ensure that all blocks have been allocated by the filesystem. This option is
164only meaningful if the -S option has been specified.
165.It Fl u
166Disable and ``unconfigure'' the device.
167.It Fl v
168Print messages to stdout describing actions taken.
169.El
170.Pp
171If no action option is given,
172.Fl c
173is assumed.
174.Pp
175The
176.Ar feature
177argument specifies a feature that can be enabled via the
178.Fl e
179option:
180.Bl -tag -width indent
181.It Dv swap
182Swapping is enabled on the special file.
183See
184.Xr swapon 2 .
185.It Dv mountro Ns = Ns Pa mount_point
186The special file is mounted read-only on
187.Ar mount_point .
188See
189.Xr mount 2 .
190.It Dv mountrw Ns = Ns Pa mount_point
191The special file is mounted read-write on
192.Ar mount_point .
193See
194.Xr mount 2 .
195.It Dv mount Ns = Ns Pa mount_point
196Same as ``mountrw=''.
197.El
198.Pp
199A configuration file contains one line per device/file pair in the form:
200.Bd -literal
201 special_file regular_file [ feature ]
202.Ed
203.Pp
204where fields are separated by white space.
205The previously described action options serve to configure, enable,
206disable or unconfigure all devices in the configuration file.
207.Sh FILES
208.Bl -tag -width /etc/vntab -compact
209.It Pa /etc/vntab
210default configuration file for
211.Fl a
212option
213.El
214.Sh EXAMPLES
215.Pp
216.Dl vnconfig vn0c /tmp/diskimage
217.Pp
218Configures the vnode disk
219.Pa vn0c .
220.Pp
221.Dl vnconfig -e vn0c /var/swapfile swap
222.Pp
223Configures
224.Pa vn0c
225and enables swapping on it.
226.Pp
227.Dl vnconfig -c -v /dev/vn0 cdimage.iso
228.Dl mount -t cd9660 -o ro /dev/vn0 /mnt
229.Pp
230Mount an ISO9660 CD image file.
231.Pp
232.Dl umount /mnt
233.Dl vnconfig -u vn0c
234.Pp
235Unmount the CD image file.
236.Pp
237.Dl vnconfig -d vn0c myfilesystem mount=/mnt
238.Pp
239Unmounts (disables)
240.Pa vn0c .
241.Pp
242.Dl vnconfig -ae
243.Pp
244Configures and enables all devices specified in
245.Pa /etc/vntab .
246.Pp
247.Dl vnconfig -s labels -c vn0 somebackingfile
248.Dl disklabel -r -w vn0 auto
249.Dl disklabel -e vn0
250.Pp
251Is an example of how to configure a file-backed VN disk with a disk label
252and to initialize and then edit the label. Once you create the label, you
253can partition your VN disk and, for example, create a filesystem on one of
254the partitions. If you are using a file as backing store, it may be possible
255to recover your VN disk after a crash by vnconfig'ing the same file again
256and using the VN configuration already stored in the file rather then
257relabeling and recreating the filesystem. It is even possible to fsck the
258VN partitions that previously contained filesystems.
259.Pp
260.Dl vnconfig -e -s labels,reserve -S 400m vn1
261.Dl disklabel -r -w vn1 auto
262.Dl newfs /dev/vn1c
263.Dl mount /dev/vn1c /usr/obj
264.Pp
265Is an example of a swap-backed VN disk configuration. This example assumes
266that you have at least 400 megabytes of swap free (and hopefully much more).
267The swap space is pre-reserved in order to maintain maximum performance.
268We then label the disk, newfs it, and mount it as /usr/obj. Swap-backed VN
269devices are recoverable after a crash if you (A) use the reserve flag, and if
270(B) the same swap is reserved as was the last time, meaning that such
271vnconfig's would have to be run in your rc.local. In general, though, you
272only use swap-backed VN devices to hold information you don't mind losing
273on every reboot.
274.Sh SEE ALSO
275.Xr mount 2 ,
276.Xr swapon 2 ,
277.Xr unmount 2 ,
278.Xr vn 4