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 swap partitions.

       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.

       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
              unneeded 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://pqxx.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)