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

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

     swapon -a | file ...
     swapoff -a	| file ...
     swapctl [-AhklsU] [-a file	... | -d file ...]

     The swapon, swapoff and swapctl utilities are used	to control swap	de-
     vices 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.

     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.	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.

     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 megabytes.

     -k	     Output values in kilobytes.

     -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.

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

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

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

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

BSD			       December	28, 2002			   BSD


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