VND(4)                    OpenBSD Programmer's Manual                   VND(4)

NAME
     vnd - Vnode Disk Driver

SYNOPSIS
     pseudo-device vnd 4

DESCRIPTION
     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 configura-
     tion file.

     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 a 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 vncon-
     fig(8) for more information.

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

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

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

SEE ALSO
     MAKEDEV(8), config(8), fsck(8), mount(8), newfs(8), vnconfig(8)

OpenBSD 2.9                    December 30, 1995                             1
