Script to switch RAID array from master to slave in Azure

switch.sh

#!/bin/sh

master=$1
slave=$2

date
echo "Assuming master down: $master"
echo "Switching to slave:   $slave"

azure vm show $master --json > /tmp/$master.json
disknum=`jq -r '.DataDisks[]|.name' /tmp/$master.json | wc -l`
maxlun=`expr $disknum - 1`

echo "$disknum disks found in $master"

for lun in `seq 0 $maxlun`
do
  echo "Detaching LUN $lun from VM $master"
  azure vm disk detach $master $lun
  azure vm disk list --json > /tmp/$master.$lun.json
done

for disk in `jq -r '.DataDisks[]|.name' /tmp/$master.json`
do
  echo "Attaching disk $disk to VM $slave"
  azure vm disk attach -c None $slave $disk
done

echo "All disks attached, now log onto $slave and run:"
echo "sudo mdadm --assemble /dev/md0 \`ls -1t /dev/sd* | head -n$disknum | xargs\`"
echo "sudo mount /dev/md0 /nfs"
date