FWIW we have pretty much stopped using clustering like that as well too; maintaining a cluster just took a lot more admin time and we too found the cluster to be "fragile" way too often.
An HA environment for us now is a Zimbra farm on identical server hardware connected to a good SAN (Clarion CX4 or similar) with a spare server chassis. If a server dies, we just pop the on-board disks from the dead box into the spare chassis, boot it up, reconfigure all the NICs (MAC addresses changed of course) and we are done. Not too much slower than waiting for the RHEL cluster to fail over.
If very serious HA is required by the client, we'll add a second SAN in a different location and do SAN replication over the (secured) WAN.
Hope that helps,
Mark
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___________________________________ L. Mark Stone, CIO  "Uptime. All the time."
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