Difference between revisions of "SwapClean"

1. !/bin/bash
2. Swap Cleaner
3. Watches swap usage
4. If there is swapping going on and there is enough free (+cache) ram, then turn swap off and back on.
5. Created by James Dooley
6. Feature / Bug requests jdooley@lw

1. User Assigned Variables

swapthresh=0 #Swap threshold for clearing swap. Will not clear until this value is hit. Good for servers that normally allocates small amounts of swap for some reason. freethresh=0 #Real free (free+cached) - current swap threshold. Ensures that atleast x bytes are free before clearing. loadthresh=0 #Load threshold, will not clear if above this value (unless 0) logrotate=1000 #Max number of lines in the log file

function plog { echo "[ `date` ][ $curswap; $curfree; $realload ] $1" >> /var/log/swapclean if [ "`wc -l /var/log/swapclean | awk '{print $1}'`" -gt "$logrotate" ] then sed -i -e "1d" /var/log/swapclean fi return }

function clearswap { plog "Clearing swap" touch .swapoff echo $$ > .swapoff /sbin/swapoff -a && /sbin/swapon -a rm -f .swapoff plog "Swap Cleared" return }

function checkswap {

curswap=`free | fgrep "Swap:" | awk '{print $3}'` curfree=`free | fgrep "buffers/cache:" | awk '{print $4}'` realload=`cat /proc/loadavg | awk '{print $1}'` curload=`echo "$realload * 100" | bc | sed 's/[.].*//'` loadthresh=`echo "$loadthresh *100" | bc | sed 's/[.].*//'` swapdif=`expr $curfree - $curswap`

if [ "$swapthresh" -lt "$curswap" ] then #Server has swapped and is above its threshold if [ "$freethresh" -lt "$swapdif" ] then #Free - Swap is greater then freethresh if [ "$curload" -lt "$loadthresh" -o "$loadthresh" -eq 0 ] then #Load is below threshold if [ ! -e ".swapoff" ] then clearswap else plog "Lock file found, swap may be already clearing" opid=`cat .swapoff` if [ ! "`ps ax | grep $opid | grep ${0##*/}`" ] then plog "PID not active or not owned by swapclean, clearing pid file" rm -f .swapoff clearswap else plog "Swap already being cleared, PID active" fi fi else plog "High load, waiting to clear swap" fi else plog "Not enough free memory, waiting to clear swap" fi fi return }

function enablecron { if [ -e "/etc/cron.d/swapclean.sh" ] then echo "Cron already enabled, use change to set new time" else echo "What time would you like to set the cron to" echo "[IE: */10 * * * * ]" read crontime; if [ ! $crontime ] then crontime="*/10 * * * *" fi echo "SHELL=/bin/bash" > /etc/cron.d/swapclean.sh echo "$crontime root $(readlink -f $0)" >> /etc/cron.d/swapclean.sh chmod 0644 /etc/cron.d/swapclean.sh echo "Cron enabled [$crontime root $(readlink -f $0)]" return fi return }

function disablecron { if [ -e "/etc/cron.d/swapclean.sh" ] then rm -f /etc/cron.d/swapclean.sh echo "Cron disabled" else echo "Cron not enabled" fi

	return

}

case $1 in

       --cron)
               case $2 in

on) enablecron ;; off) disablecron ;; change) disablecron enablecron ;; esac

               ;;
       --help)
               echo "Check swap usage:"

echo " --cron [on, change, off]" echo " on: Turns on cron job and asks for time" echo " change: Changes the cron time" echo " off: Turns off the cron job"

               ;;
       *)
               checkswap
               ;;
 esac