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NAME    [Toc]    [Back]

     vnd - Vnode Disk Driver

SYNOPSIS    [Toc]    [Back]

     pseudo-device vnd [count]

DESCRIPTION    [Toc]    [Back]

     The vnd driver provides a disk-like  interface  to  a  file.
This is useful
     for  a  variety  of  applications,  including swap files and
building miniroot
     or floppy disk images.  There are two variants,  the  traditional vnd that
     bypasses  the  buffercache  and thus is suitable for swap on
files, but not
     for building disk-images, and the svnd ("safe" vnd)  variant
that goes
     through the buffercache, thereby maintaining cache-coherency
after the
     block-device is closed which makes it suitable for  creating
disk images.
     The latter is not good for swapping on, though.

     This  document assumes that you're familiar with how to generate kernels,
     how to properly configure disks and pseudo-devices in a kernel configuration

     In  order  to compile in support for the vnd, you must add a
line similar
     to the following to your kernel configuration file:

           pseudo-device  vnd  4    # vnode disk driver

     The count argument is how many vnds memory is allocated  for
at boot time.
     In this example, no more than 4 vnds may be configured.

     There  is  a  run-time  utility that is used for configuring
vnds.  See
     vnconfig(8) for more information.

FILES    [Toc]    [Back]

     /dev/{,r}{,s}vnd* - vnd device special files.

SEE ALSO    [Toc]    [Back]

     disklabel(5), MAKEDEV(8), config(8), disklabel(8), fdisk(8),
     mount(8), newfs(8), vnconfig(8)

HISTORY    [Toc]    [Back]

     The vnd disk driver was originally written at the University
of Utah.
     The svnd variant was first seen in OpenBSD 2.1.

BUGS    [Toc]    [Back]

     The vnd driver does not work if the file does not reside  in
a local
     filesystem.  However the svnd variant does.

OpenBSD      3.6                        December     30,     1995
[ Back ]
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