I really need to know how to do this. thanks for those who will help.

1. I should have 2 zimbra opensource servers.
2. Another server will be used for the shared storage.
3. The 2 zimbra servers should have the same ip address.
4. if I shut down zimbra 1, I'll have to manually start zimbra 2 and it should be properly working just like the zimbra 1 since there is a shared storage and they are of the same ip address.