.\" $FreeBSD: src/usr.sbin/vnconfig/vnconfig.8,v 1.14.2.8 2003/01/04 22:35:53 keramida Exp $
.\" $DragonFly: src/usr.sbin/vnconfig/vnconfig.8,v 1.10 2008/07/27 22:36:01 thomas Exp $
.\"
-.Dd January 30, 2008
+.Dd September 28, 2009
.Dt VNCONFIG 8
.Os
.Sh NAME
.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. If you
-want to use swap backing store for your device instead of a file, you
-can leave
+or can contain a filesystem that is mounted in the name space.
+If you want to use swap backing store for your device instead of a file,
+you can leave
.Ar regular_file
out and specify the size of the block device
with the
.Ar special_file
will access the contents of
.Ar regular_file .
+.Pp
+A
+.Nm vn
+device is autocloned if
+.Ar special_file
+is given as
+.Pa vn ,
+the name of the resulting device is printed on stdout.
.It Fl d
Disable (if possible) the specified feature.
.It Fl e
is the same as
.Fl c .
.It Fl f Ar config_file
-Use
-.Ar config_file
-as an alternate config file.
+Specify configuration file.
+Default is
+.Pa /etc/vntab .
.It Fl g
Fiddle global options.
.It Fl l Ar special_file Ar ...
-List the VN devices and indicate which ones are in use.
+List the
+.Nm vn
+devices and indicate which ones are in use.
If a
.Ar special_file
list is given, only those devices will be described.
.Ar options ,
which is a comma separated string of options.
The list of allowed options and their meanings are:
-.Bl -tag -width "follow"
-.It Ar reserve
-Pre-reserve the blocks underlying the file or swap backing store. Currently only
-works for swap backing store. This option also disables on-the-fly freeing of
+.Bl -tag -width "reserve"
+.It Cm reserve
+Pre-reserve the blocks underlying the file or swap backing store.
+Currently only works for swap backing store.
+This option also disables on-the-fly freeing of
the underlying backing store (for example, when you remove a large file).
Use this option if you wish to avoid long-term fragmentation of the backing
-store. Also note that when this option is used, the initial contents of the
-backing store may contain garbage rather than zeros. It may even be possible to
-recover the prior contents of a swap-backed VN across a reboot if the VN device
+store.
+Also note that when this option is used, the initial contents of the
+backing store may contain garbage rather than zeros.
+It may even be possible to
+recover the prior contents of a swap-backed
+.Nm vn
+across a reboot if the
+.Nm vn
+device
is configured before any swap is allocated by the system.
-.It Ar follow
-debug flow in the
+.It Cm follow
+Debug flow in the
.Xr vn 4
driver.
-.It Ar debug
-debug data in the
+.It Cm debug
+Debug data in the
.Xr vn 4
driver.
-.It Ar io
-debug I/O in the
+.It Cm io
+Debug
+.Tn I/O
+in the
.Xr vn 4
driver.
-.It Ar all
-turn on all options.
-.It Ar none
-turn off all options.
+.It Cm all
+Turn on all options.
+.It Cm none
+Turn off all options.
.El
.It Fl s Ar options
Set
.En Cm k , m , g , t
.Sm on
.Xc
-If no regular file is specified, VN will use swap for backing store.
-This option specifies the size of the device. For example,
+If no regular file is specified,
+.Nm vn
+will use swap for backing store.
+This option specifies the size of the device.
+For example,
.Sq 23m
for
23 megabytes.
In the absence of a size modifier,
.Cm m
is implied.
-The VN device will round the size up to a machine page boundary.
-Filesystems up to 7.9 terabytes are supported. When specified along with
+The
+.Nm vn
+device will round the size up to a machine page boundary.
+Filesystems up to 7.9 terabytes are supported.
+When specified along with
a regular file, this option overrides the regular file's size insofar as
-VN is concerned.
+.Nm vn
+is concerned.
.It Fl T
-When a regular file is specified, VN will
+When a regular file is specified,
+.Nm
+will
.Fn ftruncate
the file to length 0 first.
Normally you should also specify the
.Fl S
option has been specified.
.It Fl Z
-When a regular file is specified, VN will zero the contents of the file to
-ensure that all blocks have been allocated by the filesystem. This option is
-only meaningful if the
+When a regular file is specified,
+.Nm
+will zero the contents of the file to
+ensure that all blocks have been allocated by the filesystem.
+This option is only meaningful if the
.Fl S
option has been specified.
.It Fl u
.Fl e
option:
.Bl -tag -width indent
-.It Dv swap
+.It Cm swap
Swapping is enabled on the special file.
See
.Xr swapon 2 .
-.It Dv mountro Ns = Ns Pa mount_point
+.It Cm mountro= Ns Ar mount_point
The special file is mounted read-only on
.Ar mount_point .
See
.Xr mount 2 .
-.It Dv mountrw Ns = Ns Pa mount_point
+.It Cm mountrw= Ns Ar mount_point
The special file is mounted read-write on
.Ar mount_point .
See
.Xr mount 2 .
-.It Dv mount Ns = Ns Pa mount_point
-Same as ``mountrw=''.
+.It Cm mount= Ns Ar mount_point
+Same as
+.Cm mountrw= Ns Ar mount_point .
.El
.Pp
A configuration file contains one line per device/file pair in the form:
.Bd -literal
- special_file regular_file [ feature ]
+ special_file regular_file [feature]
.Ed
.Pp
where fields are separated by white space.
option
.El
.Sh EXAMPLES
+.Dl vnconfig vn /tmp/diskimage
+.Pp
+Configures an autocloned vnode disk,
+the name of the resulting device is printed, e.g.\&
+.Pa vn4 .
+.Pp
.Dl vnconfig vn0 /tmp/diskimage
.Pp
Configures the vnode disk
.Dl disklabel -r -w vn0s0 auto
.Dl disklabel -e vn0s0
.Pp
-Is an example of how to configure a file-backed VN disk with a disk label
-and to initialize and then edit the label. Once you create the label, you
-can partition your VN disk and, for example, create a filesystem on one of
-the partitions. If you are using a file as backing store, it may be possible
-to recover your VN disk after a crash by vnconfig'ing the same file again
-and using the VN configuration already stored in the file rather than
-relabeling and recreating the filesystem. It is even possible to fsck the
-VN partitions that previously contained filesystems.
+Is an example of how to configure a file-backed
+.Nm vn
+disk with a disk label
+and to initialize and then edit the label.
+Once you create the label, you
+can partition your
+.Nm vn
+disk and, for example, create a filesystem on one of the partitions.
+If you are using a file as backing store, it may be possible
+to recover your
+.Nm vn
+disk after a crash by
+.Nm Ns 'ing
+the same file again and using the
+.Nm vn
+configuration already stored in the file rather than
+relabeling and recreating the filesystem.
+It is even possible to
+.Xr fsck 8
+the
+.Nm vn
+partitions that previously contained filesystems.
.Pp
.Dl vnconfig -e -s reserve -S 400m vn1
.Dl disklabel -r -w vn1s0 auto
.Dl newfs /dev/vn1s0
.Dl mount /dev/vn1s0 /usr/obj
.Pp
-Is an example of a swap-backed VN disk configuration. This example assumes
+Is an example of a swap-backed
+.Nm vn
+disk configuration.
+This example assumes
that you have at least 400 megabytes of swap free (and hopefully much more).
The swap space is pre-reserved in order to maintain maximum performance.
We then label the disk, newfs it, and mount it as
.Pa /usr/obj .
-Swap-backed VN
-devices are recoverable after a crash if you (A) use the reserve option, and if
+Swap-backed
+.Nm vn
+devices are recoverable after a crash if you (A) use the
+.Cm reserve
+option, and if
(B) the same swap is reserved as was the last time, meaning that such
-vnconfig's would have to be run in your rc.local. In general, though, you
-only use swap-backed VN devices to hold information you don't mind losing
-on every reboot.
+.Nm Ns 's
+would have to be run in your
+.Xr rc.local 8 .
+In general, though, you only use swap-backed
+.Nm vn
+devices to hold information you don't mind losing on every reboot.
.Sh SEE ALSO
.Xr mount 2 ,
.Xr swapon 2 ,
projects / dragonfly.git / commitdiff