I am trying to evaluate Zimbra as our successor to OCS and I have read through the docs, but I am still unsure of what level of redundancy/clustering Zimbra actually supports.
I know that Zimbra supports multi-server setup, which is where my user accounts get stored on different mailbox servers. Afaik, one can put a loadbalancer in front of those mailbox servers the mailbox servers will re-route the requests accordingly.
But what about IMAP?
Plus, wouldn't it make more sense to have a clusteres storage and have multiple mailbox servers accessing that storage?
we had a very long ticket with zimbra support regarding loadbalancing/failover/ssl offloading solution with a hardware loadbalancer. to make it short: ssl offloading is not supported by zimbra. it has somethign to do with the proxy / backend configuration. proxy thinks it is running http and returns always http urls to the user.
with some workarounds hardware loadbalancers (at least ours) is woring like a charm. zimbra has no knowledge of the failoversetup.
about routing: zimbra proxy is doing this. so you have to loadbalance the zimbra proxy servers.
2nd possibility for failover: vrrp