Yes. Especially if you're using one of the systems as a failover or you're running them as a normally active-active configuration. You want DB replication, bu

Yes. Especially if you're using one of the systems as a failover or you're running them as a normally active-active configuration. You want DB replication, but you also want to be able to take down a blue or green, apply DB updates, be able to independently access blue or green to check out your changes, then roll the world over the upgrade leg, then do the same work on the other side, check it out, and then make it available. Alternating on blue / green as the 'live' side works, too.