I have 2 Zimbra servers running in a remote datacentre, 1 (primary) on a physical server and 1 on a Virtual (Xen) server that replicates via DRBD and have HA with Heartbeat.

They are on 6.0.5_GA_2213.RHEL5_64_20100203001950 CentOS5_64 FOSS edition and I'd like to upgrade them to latest version.

It's easy to just upgrade the main server, but then if a failover happens, I think that the outdated secondary server will have problems?

I need some advice on upgrade procedures as this is a mission critical servers(s) and I cannot afford long downtimes... nor something that broke because of the upgrade.

Thanks in advance


PS: Can I just run a 'dummy' install on a temp /opt folder on the secondary using './install.sh -s' ? Then delete the dummy /opt?