Re: Zimbra server failover question

["Daniel A. Ramaley" <daniel.ramaley@drake.edu>]

We also considered something like this. We have about 12k accounts on 2 
mailbox servers (with separate LDAP and MTA servers). The LDAP and MTA 
servers now run in virtual machines on a Xen cluster, but the mailboxes 
are still physical hardware. We have a 3rd machine identical to the 2 
production machines that just sits idle in case we need it for failover.

I don't think you can have "Server A" act as failover for user group B. 
Accounts are tied to their server. If you have identical servers with 
/opt/zimbra mounted from a SAN, you can move accounts to a different 
server by mounting the same SAN storage and changing the failover 
server's IP and hostname to match, making it in effect the same as the 
failed machine. But i don't think you can combine the accounts from 2 
servers and have them run on the same installation. You'd have to 
somehow run 2 separate and isolated instances of the Zimbra software on 
the same OS. That would be hard. *Maybe* it would be possible if you 
installed Zimbra on server A to /opt/zimbra_A and on server B to 
/opt/zimbra_B (or something else unique), and then when B died, mount 
its files on /opt/zimbra_B on server A, assigned server B's IP as a 
secondary IP on server A. You'd probably have to hack Zimbra a bit to 
force it to bind to just the IP you wanted it to. Even then i'm not sure 
it would work; the software isn't designed to do that.

The obvious solution to accomplish what you want would be to install a 
virtual cluster of some sort (Xen, VMWare, whatever) on your base 
hardware, and then install Zimbra in virtual machines. If you make sure 
each physical machine has enough RAM to run at least 2 of the virtual 
machines, then it would be possible to failover. Downsides to this 
approach are having to spend a lot of money on RAM, and having the 
overhead of the VM layer. For something as I/O intensive as a mailbox 
server, i'm not sure you want that extra VM overhead.

On 2010-07-14 at 09:08:00, you wrote:
>We're currently planning our Zimbra installation and I have a question
>about Zimbra server failover.
>
>We plan to spread our 10k accounts on 3 Zimbra server machines with
>the mail stores on a SAN. One solution is to have a fourth machine as
>a hot standby.
>
>Could we use the other 2 machines as standby ?
>
>Server A
>    Master for user group A
>    Failover for user group B
>
>Server B
>    Master for user group B
>    Failover for user group C
>
>Server C
>    Master for user group C
>    Failover for user group A
>
>Thanks

-- 
Daniel A. Ramaley
Network Engineer 2

Dial Center 118, Drake University
2407 Carpenter Ave / Des Moines IA 50311 USA
Tel: +1 515 271-4540
Fax: +1 515 271-1938
E-mail: daniel.ramaley@drake.edu