NAME

       swapspace - dynamically manage swap space

SYNOPSIS

       swapspace [options]

DESCRIPTION

       Monitor  memory  and  swap  usage  and allocate or deallocate swap space as needed.  This program aims to
       reduce or do away with the need for swapfiles.

       swapspace can be built in two configurations: the full-featured one (which is now  the  default)  or  the
       unconfigurable  version.  The latter only accepts a few options, disabling all features that are probably
       only relevant to developers.  At some point in the  feature,  when  enough  confidence  exists  that  the
       various  configuration  parameters are either good enough for everyone or have been made unnecessary, the
       unconfigurable build may become the default.

       The following options are accepted in the unconfigurable version.   All  of  these  have  more  extensive
       equivalents in the full-featured version.

       -d     Quietly ignored; always enabled in unconfigurable version.

       -e     Attempt  to free up all allocated swap files.  Returns 0 if all files were successfully erased, or
              1 otherwise.

       -h     Display usage information and exit.

       -p     Write process identifier to /var/lib/swapspace.pid when starting  (and  delete  it  when  shutting
              down).  The file's name and location cannot be changed in the unconfigurable version.

       -q     Quietly ignored; always enabled in unconfigurable version.

       -v     Quietly ignored; always enabled in unconfigurable version.

       -V     Print program version information and exit.

       In most cases, these should be the only options of any interest for normal use of the program.  All files
       are kept in their default locations, which were chosen in accordance with the Linux Filesystem  Hierarchy
       Standard,  and  algorithmic parameters are left at defaults that have been tested to work well for a wide
       range of uses.

       The full-featured configuration accepts more options, as listed below.  The long-format options may  also
       be specified, without the leading "--", in a configuration file.  By default, /etc/swapspace.conf is read
       on startup.

       -a duration, --cooldown=duration
              If disk space runs out when allocating a swapfile, wait for duration iterations  (of  roughly  one
              second  each)  before  considering  allocating  one  again;  or if space doesn't run out, wait for
              duration iterations before  considering  deallocating  uneeded  swapfiles.   This  stabilizes  the
              daemon's behaviour in the face of varying memory requirements.

       -B p, --buffer_elasticity=p
              Consider p% of system-allocated I/O buffers to be available for other use.

       -c file, --configfile=file
              Read file instead of the default configuration file.

       -C p, --cache_elasticity=p
              Consider p% of filesystem cache to be available for other use.

       -d, --daemon
              Run quietly in the background.  This is the normal way to run the program.

       -e, --erase
              Attempt  to free up all allocated swap files.  Returns 0 if all files were successfully erased, or
              1 otherwise.

       -f p, --freetarget=p
              Aim to have p% of combined memory and swap space free.

       -h, --help
              Display usage information and exit.

       -l p, --lower_freelimit=p
              Try to keep at least p% of combined memory and  swap  space  free;  if  less  than  p  percent  is
              available, attempt to allocate more swap space.

       -M size, --max_swapsize=size
              Never  let  swapfiles  become  larger  than  size bytes.  You don't normally need to set this; the
              daemon will learn when its swap files get too big and adapt automatically.

       -m size, --min_swapsize=size
              Never bother to allocate any swapfiles smaller than size bytes.  There should be no need to change
              this variable except for testing.

       -p [file], --pidfile[=file]
              Write  process  identifier to file when starting (and delete file when shutting down); defaults to
              /var/lib/swapspace.pid.

       -P, --paranoid
              Overwrite retired swapfiles before they are deleted, so an attacker who obtains access to the disk
              without going through the system's access control checks (e.g. by unplugging the computer and then
              rebooting from a CD) cannot retrieve the swapped data.  There is no guarantee that this will work,
              and  it  will not thwart advanced forensic analysis using custom-built hardware; but it may reduce
              the chances of an attacker with physical access to the system  obtaining  passwords,  credit  card
              numbers  etc.   The  program  will  attempt  to free up all allocated swapfiles on termination and
              return a success code for this cleanup, as if the --erase had been specified.

       Caution
              The --paranoid option will slow down swap file management considerably.  In  particular,  stopping
              the  daemon  will cause it to try and deallocate (and wipe) all swapfiles it has created, and they
              will not be available for swapping immediately after reboot.

       -q, --quiet
              Suppress informational output.

       -s dir, --swappath=dir
              Create swapfiles in directory dir instead of default location /var/lib/swapspace.   This  location
              must  be  accessible  to  root  only; allowing anyone else to write to this directory or even read
              swapped data would be a serious security breach.

       -u p, --upper_freelimit=p
              Avoid having more than p% of combined memory and swap space free; if this percentage is  exceeded,
              try to deallocate swap space.

       -v, --verbose
              Log debug information to system log and/or standard output, as appropriate.

       -V, --version
              Print program version information and exit.

       Numbers  may  be  suffixed  with  k,  m,  g or t to indicate kilobytes, megabytes, gigabytes or terabytes
       respectively: 1k means 1024 bytes, 1m means 1024 kilobytes, 4g means 4096 megabytes and so on.

       Timings are measured in iterations, which should typically last about one second each.   No  pretense  of
       accurate timing is made; this is not the kind of program you would run on a hard-realtime system.

       Any  messages  are sent to the system daemon log; it is also printed to the standard output/error streams
       (as appropriate based on the urgency of each individual message) if available.

SIGNALS

       State information can be logged by sending the program the SIGUSR1 signal (user-defined signal  1).   Not
       all  of  this  information  will always be current; most of the information internal to swapspace is only
       updated when needed.

       Sending the SIGUSR2 signal will make the program free all swapfiles that are not  currently  needed,  and
       abstain  from allocating any more for the timespan of one cooldown period.  The program will behave as if
       it just tried to create a swapfile but ran out of disk space.

FILES

        /etc/init.d/swapspace  /etc/swapspace.conf  /usr/sbin/swapspace  /var/lib/swapspace/

AUTHOR

       Written by Jeroen T. Vermeulen

BUGS

       Please    report     any     bugs     you     may     find     on     the     project     website     at:
       http://thaiopensource.org/development/swapspace/

COPYRIGHT

       Copyright © 2005 Software Industry Promotion Agency (SIPA), Thailand
       This  is  free  software;  see  the source for copying conditions.  There is no warranty whatsoever.  Use
       entirely at your own risk.

SEE ALSO

       kill(1), mkswap(8), signal(7), swapon(2), swapoff(2), swapon(8), swapoff(8)