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SWAPON(8)		FreeBSD	System Manager's Manual		     SWAPON(8)

NAME
     swapon, swapoff, swapctl -- specify devices for paging and	swapping

SYNOPSIS
     swapon [-F	fstab] -aq | file ...
     swapoff [-F fstab]	-aq | file ...
     swapctl [-AghklmsU] [-a file ... |	-d file	...]

DESCRIPTION
     The swapon, swapoff and swapctl utilities are used	to control swap
     devices in	the system.  At	boot time all swap entries in /etc/fstab are
     added automatically when the system goes multi-user.  Swap	devices	use a
     fixed interleave; the maximum number of devices is	specified by the ker-
     nel configuration option NSWAPDEV,	which is typically set to 4.  There is
     no	priority mechanism.

     The swapon	utility	adds the specified swap	devices	to the system.	If the
     -a	option is used,	all swap devices in /etc/fstab will be added, unless
     their ``noauto'' option is	also set.  If the -q option is used informa-
     tional messages will not be written to standard output when a swap	device
     is	added.

     The swapoff utility removes the specified swap devices from the system.
     If	the -a option is used, all swap	devices	in /etc/fstab will be removed,
     unless their ``noauto'' option is also set.  If the -q option is used
     informational messages will not be	written	to standard output when	a swap
     device is removed.	 Note that swapoff will	fail and refuse	to remove a
     swap device if there is insufficient VM (memory + remaining swap devices)
     to	run the	system.	 The swapoff utility must move swapped pages out of
     the device	being removed which could lead to high system loads for	a
     period of time, depending on how much data	has been swapped out to	that
     device.

     Other options supported by	both swapon and	swapoff	are as follows:

     -F	fstab
	     Specify the fstab file to use.

     The swapctl utility exists	primarily for those familiar with other	BSDs
     and may be	used to	add, remove, or	list swap devices.  Note that the -a
     option is used differently	in swapctl and indicates that a	specific list
     of	devices	should be added.  The -d option	indicates that a specific list
     should be removed.	 The -A	and -U options to swapctl operate on all swap
     entries in	/etc/fstab which do not	have their ``noauto'' option set.

     Swap information can be generated using the swapinfo(8) utility, pstat
     -s, or swapctl -l.	 The swapctl utility has the following options for
     listing swap:

     -h	     Output values in human-readable form.

     -g	     Output values in gigabytes.

     -k	     Output values in kilobytes.

     -m	     Output values in megabytes.

     -l	     List the devices making up	system swap.

     -s	     Print a summary line for system swap.

	     The BLOCKSIZE environment variable	is used	if not specifically
	     overridden.  512 byte blocks are used by default.

FILES
     /dev/{ad,da}?s?b  standard	paging devices
     /dev/md?	       memory disk devices
     /etc/fstab	       ASCII file system description table

DIAGNOSTICS
     These utilities may fail for the reasons described	in swapon(2).

SEE ALSO
     swapon(2),	fstab(5), init(8), mdconfig(8),	pstat(8), rc(8)

HISTORY
     The swapon	utility	appeared in 4.0BSD.  The swapoff and swapctl utilities
     appeared in FreeBSD 5.1.

FreeBSD	9.3			 June 23, 2008			   FreeBSD 9.3

NAME | SYNOPSIS | DESCRIPTION | FILES | DIAGNOSTICS | SEE ALSO | HISTORY

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