Why not keep storage2 and OS on the current PERC740P and get another HBA for creating a new zpool with direct access to the disks and special device?
If you have enough disks you can first do an offline copy of the current datastore from storage1...
stooopid question, what about removable datastores and a tool less icydock to juggle a couple harddrives in rotation for offline/cold storage
sure someone needs to put em in once in a while, could be done for some monthly thing
sync on mount job...