I been working on for about a month and half on setup drbd and nfs. I keep running into issue with the way heartbeat/pacemaker handles nfs. Does anyone know a good way to set up a HA NFS server with DRBD and Heartbeat and NFS. I am willing to share my pain in setting it up.
It involves a bit of manual work which all depends on how seamless you want failover. Which I assume is your problem so far. Client mount options play a more significant role in this setup.
The drbd part is trivially provided by the included scripts. It will promote/demote from sec to pri as needed. The NFS part involves some work.
http://sources.redhat.com/cluster/doc/nfscookbook.pdf
If I can offer a small suggestion, if you're on CentOS, use the boxed RHCS, its very good to understate it. Drop pacemaker, but that's my $0.02 CAN:) It's as simple as yum install with some cluster.conf tweaking and voila to setup a cluster. If you don't care about the locks/states being available on the secondary when it gets promoted (I assume you're not using a cluster FS and running pri/pri) then it's easy. When I was learning RHCS I recall symlinking the appropriate dirs on the replicated block device.
HTH, jlc