1.\" Copyright (c) 1980, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)swapon.8 8.1 (Berkeley) 6/5/93 33.\" $FreeBSD: src/sbin/swapon/swapon.8,v 1.15.2.2 2001/12/14 15:17:56 ru Exp $ 34.\" $DragonFly: src/sbin/swapon/swapon.8,v 1.4 2007/08/10 18:28:27 swildner Exp $ 35.\" 36.Dd June 5, 1993 37.Dt SWAPON 8 38.Os 39.Sh NAME 40.Nm swapon 41.Nd "specify additional device for paging and swapping" 42.Sh SYNOPSIS 43.Nm 44.Fl a 45.Nm 46.Ar special_file ... 47.Sh DESCRIPTION 48.Nm Swapon 49is used to specify additional devices on which paging and swapping 50are to take place. 51The system begins by swapping and paging on only a single device 52so that only one disk is required at bootstrap time. 53Calls to 54.Nm 55normally occur in the system multi-user initialization file 56.Pa /etc/rc 57making all swap devices available, so that the paging and swapping 58activity is interleaved across several devices. 59.Pp 60Normally, the first form is used: 61.Bl -tag -width indent 62.It Fl a 63All devices marked as ``sw'' 64swap devices in 65.Pa /etc/fstab 66are made available unless their ``noauto'' option is also set. 67.El 68.Pp 69The second form gives individual block devices as given 70in the system swap configuration table. The call makes only this space 71available to the system for swap allocation. 72.Sh FILES 73.Bl -tag -width "/dev/{ad,da}?s?b" -compact 74.It Pa /dev/{ad,da}?s?b 75standard paging devices 76.It Pa /dev/vn?s?b 77vnode disk paging device 78.It Pa /etc/fstab 79ASCII filesystem description table 80.It Pa /etc/vntab 81ASCII vnode file table 82.El 83.Sh SEE ALSO 84.Xr swapon 2 , 85.Xr fstab 5 , 86.Xr init 8 , 87.Xr pstat 8 , 88.Xr rc 8 , 89.Xr vnconfig 8 90.Sh HISTORY 91The 92.Nm 93command appeared in 94.Bx 4.0 . 95.Sh BUGS 96There is no way to stop paging and swapping on a device. 97It is therefore not possible to dismount swap devices which are 98mounted during system operation. 99