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LUN Balancing Script

Trolling the VMTN forums today I came across something interesting, a script to balance the LUNs on your ESX hosts across multiple paths:

for PATHS in 2 4 6 8
do
  STPATHS=${PATHS}
  COUNTER="1"
 
  for LUN in $(esxcfg-mpath -l | grep "has ${STPATHS} paths" | awk '{print $2}')
  do
     esxcfg-mpath --lun=${LUN} --path=$(esxcfg-mpath -q --lun=${LUN} |\
     grep FC | awk '{print $4}' | awk '{print NR "S\t " $0}' | \
     grep ${COUNTER}S | awk '{print $2}') --preferred
     COUNT=`expr ${COUNTER} + 1`
     COUNTER=${COUNT}
     if [[ ${COUNTER} -gt ${STPATHS} ]]
     then
        COUNTER="1"
     fi
  done
done

Credit goes to KidE for writing the script. I find this to be very interesting as I see Disk I/O as being the largest bottleneck in ESX today ( only experimental Round-Robin mlutipathing is currently available in ESX 3.5.0 ).

Posted by Dominic Rivera at Monday, March 31, 2008.