1.\" $NetBSD: vnd.4,v 1.1 1995/12/30 18:10:48 thorpej Exp $ 2.\" 3.\" Copyright (c) 1995 Jason R. Thorpe. 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed for the NetBSD Project 17.\" by Jason R. Thorpe. 18.\" 4. Neither the name of the author nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 27.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" $FreeBSD: src/share/man/man4/vn.4,v 1.6.2.4 2002/04/15 05:48:55 asmodai Exp $ 35.\" $DragonFly: src/share/man/man4/vn.4,v 1.6 2007/06/14 21:16:13 swildner Exp $ 36.\" 37.Dd September 28, 2009 38.Dt VN 4 39.Os 40.Sh NAME 41.Nm vn 42.Nd vnode disk driver 43.Sh SYNOPSIS 44.Cd pseudo-device vn Op n 45.Pp 46Alternatively, to load the driver as a module at boot time, place the 47following line in 48.Pa /boot/loader.conf : 49.Bd -literal -offset indent 50vn_load="YES" 51.Ed 52.Sh DESCRIPTION 53The 54.Nm 55driver uses swap or a file as backing store to abstract-out a 56device which may then be used like a disk. 57The 58.Nm 59driver supports both labeled and unlabeled pseudo-disks and is useful for 60a variety of applications, including swap files and building mini-root, 61floppy, or CD-ROM disk images. 62.Nm 63may also be used to create temporary swap-backed filesystems, such as 64.Pa /tmp , 65in a somewhat less memory-hungry manner than MFS. 66.Pp 67The 68.Nm 69driver supports autocloning. By default 4 70.Nm 71devices are also precreated. 72.Sh FILES 73.Bl -tag -width "Pa /dev/vn*" -compact 74.It Pa /dev/vn* 75.Nm 76device special files 77.El 78.Sh SEE ALSO 79.Xr fsck 8 , 80.Xr mount 8 , 81.Xr mount_mfs 8 , 82.Xr newfs 8 , 83.Xr vnconfig 8 84.Sh HISTORY 85The vnode disk driver was originally written at the University of 86Utah and was substantially modified by 87.Fx 88developers to add swap-backed support. 89.Sh BUGS 90The 91.Nm 92driver does not work if the file does not reside in a local filesystem. 93