DPHYS-SWAPFILE(8)					      System Manager's Manual						 DPHYS-SWAPFILE(8)

NAME

       dphys-swapfile - set up, mount/unmount, and delete an swap file

SYNOPSIS

       dphys-swapfile setup|swapon|swapoff|uninstall

DESCRIPTION

       dphys-swapfile  computes  the size for an optimal swap file (and resizes an existing swap file if necessary), mounts an swap file, unmounts
       it, and and delete it if not wanted any more.

OPTIONS

       There is only one parameter, an command, which can be either of these:

       setup  Tells dphys-swapfile to compute the optimal swap file size and (re-)generate an fitting swap file. Default it 2 times RAM size. This
	      can be called at boot time, so the file allways stays the right size for current RAM, or run by hand whenever RAM size has changed.

       swapon and  swapoff These run the swapon and swapoff commands on the swapfile. Note that direct swapon/off from /etc/fstab is not possible,
	      as that is (at least on Debian) done in the same script that mounts /var (which is where the swap file most likely resides). And	we
	      need to do our setup between those actions. So pass up /etc/fstab, and do our own swapon/off.

       uninstall
	      Gets rid of an unwanted swap file, reclaiming the disk space.

CONFIG

       The config file /etc/dphys-swapfile allows the user to set up the working environment for dphys-swapfile.

       This config file is a sh script fragment full of assignments, which is sourced. Standard sh syntax rules apply. Assignments are:

       CONF_SWAPFILE
	      Set  where  the swap file should be placed. Defaults to /var/swap. It is unlikely that you will need to change this, unless you have
	      very strange partitioning, and then you will most likely be using an swap partition anyway.

       CONF_SWAPSIZE
	      Force file size to this. Default is 2*RAM size. This is unlikely to be needed, unless in strange	diskspace  situations.	Note  that
	      swap enabled and smaller than RAM causes kernal-internal VM trouble on random systems.

       CONF_SWAPFACTOR
	      Set the relation between RAM and swap size. Must be an integer. Defaults to 2 which means swap size = 2 * RAM size

       CONF_MAXSWAP
	      Set  maximum  size of the swap file in MBytes. Defaults to 2048 which was the former kernel limit for the swapfile size and is now a
	      limit to prevent unusual big swap files on systems with a lot of RAM.

FILES

       /etc/dphys-swapfile
	      user config

       $CONF_SWAPFILE
	      the swap file, target of the whole action (defaults to /var/swap)

EXAMPLES

       dphys-swapfile is usually run at system startup and shutdown from an /etc/init.d (or /etc/rc.d) script, such as this (minimal) one:

       #!/bin/sh
       # /etc/init.d/dphys-swapfile - automatically set up an swapfile
       # author franklin, last modification 2004.06.04
       # This script is copyright ETH Zuerich Physics Departement,
       #   use under either modified/non-advertising BSD or GPL license
       case "$1" in
	 start)
	   /sbin/dphys-swapfile setup
	   /sbin/dphys-swapfile swapon
	   ;;
	 stop)
	   /sbin/dphys-swapfile swapoff
	   ;;
       esac
       exit 0

       If an sysadmin wants to have his swapfile in annother place, say /var/run/swap, he can use:

       In /etc/dphys-swapfile:

       CONF_SWAPFILE=/var/run/swap

AUTHOR

       franklin@phys.ethz.ch, http://www.phys.ethz.ch/~franklin/

D-PHYS Swapfile Tools						    2006.09.15							 DPHYS-SWAPFILE(8)