Currently I'm using M/Monit to monitor a lot of instances at once. But Iwould also like to know if anyone tried to monitor Disk I/O with monit? I don't have any good knowledge about disks, so if someone could point me to the right direction or share some shell script would be great!
I wonder if this is what you're looking for:
check filesystem datafs with path /dev/sdb1
group server
start program = "/bin/mount /data"
stop program = "/bin/umount /data"
if failed permission 660 then unmonitor
if failed uid root then unmonitor
if failed gid disk then unmonitor
if space usage > 80 % then alert
if space usage > 94 % then stop
if inode usage > 80 % then alert
if inode usage > 94 % then stop
alert root@localhost
Taken from: http://mmonit.com/monit/documentation/monit.html#examples