[ceph-users] how many monitor should to deploy in a 1000+ osd cluster

hi all: I have a  production cluster, and it had 24 hosts (528 osds,3mons) at a former. Now we want to add 36 hosts so the osd increase to 1320 .  does the monitor need to increase?how many numbers of monitor node is recommended?        Another question is which monitor does monclient  commnuicate with? And how it decide?  Any suggestions are welcome!