This is quite an interesting subject. We've been exploring our possibilities with this as well. You definitely want to look into the detach/attach mechanism. Cloning isn't useful here, since you don't need to "clone" any data, it's already on the SAN. What you're doing is actually "moving" a zone. Have you looked at this?

Solaris Operating System - Move a Solaris Containers How To Guide

However, I must say, if you want a true "redundancy" solution you'll be wanting some kind of other solution sooner or later. Maybe two zones that are constantly up, that share their application data on the SAN....? Eventually it's much better to put up some kind of cluster: either on application level (e.g. Weblogic cluster, Oracle RAC) or else on OS level (SUN cluster). Or on both levels, if you're so inclined.

That said, there are still options left to play with the idea of being able to boot a zone on another machine at any time. We've been wondering about this as well: If we have zones on a SAN volume, can we boot them on another server? Well, if you use the detach/attach mechanism, it will work. You'll just have to recreate the zone config (zonecfg) on the second machine.
One easy way to do this, is to export the config on machine A and import it on machine B. You could even store the config on the SAN. If the SAN volume is visible on both machines, you could do:

Code:

machinea# zonecfg -z zone1 export > /SAN/zone_configs/zone1
machinea# zoneadm -z zone1 detach

machineb# zonecfg -z zone1 -f /SAN/zone_configs/zone1
machineb# zoneadm -z zone1 attach
machineb# zoneadm -z zone1 boot

Voila. There isn't more to it than that. (Make sure both machines have the same patchlevel and the attach should work fine).

However, this is all great, IF you can do the detach/attach. If you use this as a redundancy option, when machine A crashes you won't be able to do the detach... Do you know if there's a way to an attach without the detach? We haven't tested it yet. Either way, I'd be interested in hearing about any solutions you've implemented.