1.\" $OpenBSD: vnd.4,v 1.6 1998/03/10 04:50:46 millert Exp $ 2.\" $NetBSD: vnd.4,v 1.1 1995/12/30 18:10:48 thorpej Exp $ 3.\" 4.\" Copyright (c) 1995 Jason R. Thorpe. 5.\" All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed for the NetBSD Project 18.\" by Jason R. Thorpe. 19.\" 4. Neither the name of the author nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 24.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 27.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 28.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 29.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 30.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 31.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.Dd December 30, 1995 36.Dt VND 4 37.Os OpenBSD 38.Sh NAME 39.Nm vnd 40.Nd Vnode Disk Driver 41.Sh SYNOPSIS 42.Cd "pseudo-device vnd 4" 43.Sh DESCRIPTION 44The 45.Nm 46driver provides a disk-like interface to a file. This is useful for 47a variety of applications, including swap files and building miniroot 48or floppy disk images. There are two variants, the traditional 49.Nm 50that bypasses the buffercache and thus is suitable for swap on files, but 51not for building disk-images, and the 52.Nm svnd 53("safe" 54.Nm 55) variant that goes 56through the buffercache, thereby maintaining cache-coherency after the 57block-device is closed which makes it suitable for creating disk images. 58The latter is not good for swapping on, though. 59.Pp 60This document assumes that you're familiar with how to generate kernels, 61how to properly configure disks and pseudo-devices in a kernel 62configuration file. 63.Pp 64In order to compile in support for the 65.Nm 66, you must add a line similar 67to the following to your kernel configuration file: 68.Bd -unfilled -offset indent 69pseudo-device vnd 4 # vnode disk driver 70.Ed 71.Pp 72The count argument is how many 73.Nm vnds 74memory is allocated for a boot time. In this example, no more than 4 75.Nm vnds 76may be configured. 77.Pp 78There is a run-time utility that is used for configuring 79.Nm vnds . 80See 81.Xr vnconfig 8 82for more information. 83.Sh BUGS 84The 85.Nm 86driver does not work if the file does not reside in a local filesystem. 87However the 88.Nm svnd 89variant does. 90.Sh FILES 91/dev/{,r}{,s}vnd* - vnd device special files. 92.Pp 93.Sh HISTORY 94The vnode disk driver was originally written at the University of 95Utah. The svnd variant was first seen in 96.Ox 2.1 . 97.Sh SEE ALSO 98.Xr MAKEDEV 8 , 99.Xr config 8 , 100.Xr config.old 8 , 101.Xr fsck 8 , 102.Xr mount 8 , 103.Xr newfs 8 , 104.Xr vnconfig 8 . 105