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DESCRIPTION

Options indicate an action to be performed:

-a

Read a command file and performs the specified actions for each device/file pair.

-c

Configure the device. If successful, references to special_file will access the contents of regular_file.

A vn device is autocloned if special_file is given as vn, the name of the resulting device is printed on stdout.

-d

Disable (if possible) the specified feature.

-e

Configure the device and enables any feature that was specified. If no feature was specified, -e is the same as -c.

-f config_file

Specify configuration file. Default is /etc/vntab.

-g

Fiddle global options.

-l special_file ...

List the vn devices and indicate which ones are in use. If a special_file list is given, only those devices will be described.

-r options

Reset options, which is a comma separated string of options. The list of allowed options and their meanings are:

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 is configured before any swap is allocated by the system.

follow

Debug flow in the vn(4) driver.

debug

Debug data in the vn(4) driver.

io

Debug I/O in the vn(4) driver.

all

Turn on all options.

none

Turn off all options.

-s options

Set options, which is a comma separated string of options. The list of allowed options and their meanings are the same as for the -r option.

-S value{k,m,g,t}

If no regular file is specified, vn will use swap for backing store. This option specifies the size of the device. For example, ‘23m’ for 23 megabytes. In the absence of a size modifier, 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 a regular file, this option overrides the regular file's size insofar as vn is concerned.

-T

When a regular file is specified, vnconfig will ftruncate() the file to length 0 first. Normally you should also specify the -S option to set the size of the file. This option also creates the file if it did not previously exist. This option is only meaningful if the -S option has been specified.

-Z

When a regular file is specified, vnconfig 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 -S option has been specified.

-u

Disable and ``unconfigure'' the device.

-v

Print messages to stdout describing actions taken.

If no action option is given, -c is assumed.

The feature argument specifies a feature that can be enabled via the -e option:

swap

Swapping is enabled on the special file. See swapon(2).

mountro=mount_point

The special file is mounted read-only on mount_point. See mount(2).

mountrw=mount_point

The special file is mounted read-write on mount_point. See mount(2).

mount=mount_point

Same as mountrw=mount_point.

A configuration file contains one line per device/file pair in the form:

	special_file	regular_file	[feature]

where fields are separated by white space. The previously described action options serve to configure, enable, disable or unconfigure all devices in the configuration file.