ZFS on a shared iSCSI

Hello guys, I'm not 100% this is the correct list to ask this question, if
not please feel free to point me in the right direction.

I was wondering what could be the best recipe to have an HA cluster sharing
an external ZFS storage.

Let's say I have two servers running a bunch of Jails and, thus, I'd like
to use ZFS as the underlying storage layer and I have an external (iSCSI)
storage connected.

Would it be "easily possible" to have some (2?) iSCSI LUN exposed to both
servers and then activate the pool on one or the other server?

The idea would be to reactivate the filesystem from server A on server B if
the server A fails.

Would it be "easier" to replicate everything and zfs send datas back and
forth? Clearly that would mean doubling datas and havin a scheduled replica
with a possible delay in data replication, so I'd like to avoid this.

Any thoughts?

Thanks a lot.

-- 
*Andrea Brancatelli*