Clustered Monitoring with Nagios

Hi guys

Currently have one Nagios server for monitoring and would like to add some kind of HA aspect to the monitoring system. I have seen a few complex methods including DRBD and pacemaker. Looks like a very high level of complexity for the HA aspect. Nagios doesn't seem to have much support for HA.

Anybody got any other suggestions for Nagios HA probably some kind of active/passive setup. Or what is everybody else using?

Thanks William