DR is used when you have a cluster in one location and a cluster in a separate location.
HA is used between nodes in one cluster
When I say cluster, I refer to a single-node or three-node as they can be both. HA is only used in three-node clusters.
Yes, you can run 3+3+1 DR, which uses two three-node clusters. Each three-node cluster has to be in HA mode to be able to function properly.
In your DR environment, DR should have been paused first before updating the CIMC as this will cause the appliance to reboot. Was DR paused first?