I realize hot backups are not supported in the FOSS version of Zimbra, however this is a requirement for our deployment (cold backups just aren't good enough). I think I have come up with a solution and just wanted to run it by some people here before I start buying more hardware.
I have /opt on it's own LVM volume. Setup DRBD to replicate this volume to some other node also running LVM. A script on the backup node would halt replication, take a snapshot and start replication again (DRBD would automatically get all updates it missed). Then we can do whatever we want with the snapshot.
Any reason this wouldn't work?