Linux heartbeat hiccups -
I installed a pair of clustered debian linux servers today, using the heartbeat package for failover management. I had a couple of problems (which were both my own fault) which caused the master node to keep taking over without telling the slave to shut down resulting in both machines trying to host the same IP.

Here is what not to do:
* Map hostnames to incorrect ip addresses in your hosts file.
* Have different broadcast addresses on the two nodes (be careful with this one, if you don't manually enter the correct broadcast address in debian, there's a good chance debian will guess - and guess incorrectly)

Now that I've sorted out those mistakes, failover works like a charm.

-Jonesy