How can I prevent, the health monitor from disabling all pool members?

One quick option to try is increasing the interval/timeout on the monitor itself. If you're happy that a pool member is still marked up even if it is slow to respond then increasing these options could help.

 

N

 

Hi Nathan,

 

Thanks ... I got same suggestion from my F5 call as well. It dose not solve my problem. Now I started looking into external monitor.

 

I appreciate your help. Thanks again, -Gopi

 

Not sure what benefit the monitor you are after will bring. Isn't the monitor doing what it's supposed to do, i.e. marking down (disallowing new connections to) a server/service that the user cannot use anyway?

 

Or you can simply disable the monitor altogether.

 

I was able to write a custom external health monitor which checks before disabling a pool member. But this monitor spikes the F5 CPU by 50%. Here is my script...any suggestions to reduce the cpu usage are welcome.

!/bin/sh Arguments required are Debug optional, pool name, uri & return string to look for

DEBUG=0

Verify DEBUG value

if [ -z "$DEBUG" ]

then

DEBUG=0

fi

if [ ! "$POOL_NAME" ] || [ ! "$URI" ] || [ ! "$STR_TO_LOOK" ]

then

echo "Missing value for either POOL_NAME,URI or STR_TO_LOOK" | logger -p local0.debug

exit

fi

if [ $DEBUG -eq 1 ]; then echo "The script is working! " | logger -p local0.debug;fi

IP=

echo $1 | sed 's/::ffff://'

PORT=$2

POOL_NAME=$POOL_NAME

URI=$URI

STR_TO_LOOK=$STR_TO_LOOK

NODENAME=

echo y | /usr/bin/tmsh list /ltm node |grep -B 1 $IP |grep "ltm node"|awk '{print $3}'

PIDFILE="/var/run/

basename $0

.$IP.$PORT.pid"

TOTAL_MEMBERS=

/usr/bin/tmsh show /ltm pool $POOL_NAME members all-properties | grep -c "Pool Member"

BLACKLIST_LIMIT=$(($TOTAL_MEMBERS/2))

FILENAME=/tmp/$POOL_NAME.log

if [ $DEBUG -eq 1 ]; then echo "Pool:$POOL_NAME, Uri:$URI, StringToLook: $STR_TO_LOOK, NodeName:$NODENAME,Tm:$TOTAL_MEMBERS,Blist:$BLACKLIST_LIMIT,FileName:$FILENAME" | logger -p local0.error; fi

if [ -f $PIDFILE ] then

if [ $DEBUG -eq 1 ]; then echo "EAV

basename $0

($$): pid file is present, killing process..." | logger -p local0.debug; fi

kill -9

cat $PIDFILE

> /dev/null 2>&1

echo "EAV

basename $0

($$): exceeded monitor interval, needed to kill ${IP}:${PORT} with PID

cat $PIDFILE

" | logger -p local0.error

fi

curl -fNs http://${IP}:${PORT}${URI} | grep -i "${STR_TO_LOOK}" 2>&1 > /dev/null

RCURL=$?

if [ $DEBUG -eq 1 ]; then echo "curl -fNs http://${IP}:${PORT}${URI} | grep -i "${STR_TO_LOOK}" 2>&1 > /dev/null curl_resonse:$RCURL " | logger -p local0.debug;fi

if [ $RCURL -eq 0 ]

then

 /usr/bin/tmsh list ltm pool $POOL_NAME members {$NODENAME:$PORT} | grep -E '(user-disabled|down)' 2>&1 > /dev/null

 RD=$?

 if [ $DEBUG -eq 1 ]; then echo "$POOL_NAME:$NODENAME Response value from (user-disabled|down) check: $RD" | logger -p local0.debug;fi

 if [ $RD -eq 0 ]

 then        

     /usr/bin/tmsh modify ltm pool $POOL_NAME members modify {$NODENAME:$PORT { session user-enabled}} 2>&1 > /dev/null          

     (
          flock -n 9 || exit 1

          AVALIABLE_MEMBERS=`/usr/bin/tmsh show /ltm pool $POOL_NAME members all-properties | grep -i "State" | awk {'print $NF'} |grep -ic "enabled"` 

          let "AVALIABLE_MEMBERS-=1" 

          echo $AVALIABLE_MEMBERS > $FILENAME               

       ) 9> $FILENAME  

          AVALIABLE_MEMBERS=`cat $FILENAME | awk '{print $1}'`

     if [ $DEBUG -eq 1 ]; then echo "$POOL_NAME:$NODENAME Response value from (Session user-enabled): $?" | logger -p local0.debug;fi   

 fi

 rm -f $PIDFILE

Any value to standardOut will enable the member

echo "UP"

else

if [ $TOTAL_MEMBERS -gt 1 ] 

then    

if [ $DEBUG -eq 1 ]; then echo "/usr/bin/tmsh show /ltm pool $POOL_NAME members all-properties | grep -i "State" | awk {'print $NF'} |grep -ic "enabled" " | logger -p local0.debug;fi

   (
          flock -n 9 || exit 1

          AVALIABLE_MEMBERS=`/usr/bin/tmsh show /ltm pool $POOL_NAME members all-properties | grep -i "State" | awk {'print $NF'} |grep -ic "enabled"` 

          let "AVALIABLE_MEMBERS-=1" 

          echo $AVALIABLE_MEMBERS > $FILENAME   

         ) 9> $FILENAME   

    AVALIABLE_MEMBERS=`cat $FILENAME | awk '{print $1}'`

  if [ $DEBUG -eq 1 ]; then echo "Pool $POOL_NAME details:$NODENAME Total no.of pool members:$TOTAL_MEMBERS, Avaliable no.of members:$AVALIABLE_MEMBERS,Number of members can be black listed:$BLACKLIST_LIMIT" | logger -p local0.debug;fi

  if [ $DEBUG -eq 2 ]; then echo " $NODENAME - Avaliable:$AVALIABLE_MEMBERS - Blacklist:$BLACKLIST_LIMIT" | logger -p local0.debug;fi

   if [ $AVALIABLE_MEMBERS -gt $BLACKLIST_LIMIT ]  

   then

        /usr/bin/tmsh modify ltm pool $POOL_NAME members modify {$NODENAME:$PORT { session user-disabled }} 2>&1 > /dev/null  

        if [ $DEBUG -eq 1 ]; then echo "$POOL_NAME:$NODENAME Response value from (session user-disabled) check: $?" | logger -p local0.debug;fi 

   fi 

fi

rm -f $PIDFILE

echo "Down" 

if [ $DEBUG -eq 1 ]; then echo "End of the Script" | logger -p local0.debug;fi

exit           

fi

END