We are currently running Zimbra single-server 5.0.10 on a Debian server. We essentially would like to have a Zimbra hot-standby server. Now, the easy way would be to do regular rsync's, but to the best of my knowledge, this should only be done after stopping Zimbra, rsync'ing, and then starting Zimbra again. All of which would mean that we can't rsync too often and, if the primary server fails, the backup would not be completely up to date.
I've been trying to get a good understanding of Zimbra multi-server, but I can't seem to find any information as to what it exactly does and what makes it multi-server... Does it replicate the accounts, or is it more of a cluster with some data here and some there and therefore just as susceptible to problems if one server dies?
If multi-server is not what we are looking for, what alternatives are there? The whole DRBD setup seems a bit daunting, is there anything simpler or is this the only realistic option?