I understand one of the HA solution for single-node / scale-up installations HANA is HANA System Replication. For Scale-Out installations, one or more standby node(s) do provides some level of HA (via the Host-Auto Failover method), however it does not provide protection from multiple failures. Some possible extreme designs might be to:
- Add a standby node after every 'n' nodes (where n<=2).This I believe can be accomplished using the host group concept in HANA.
- Create a complete isolated 'n' to 'n' HA system, i.e. if primary has 4 nodes, create another 4 nodes of secondary system and setup system replication. This feels like an expensive solution for HA (maybe okay for DR).
Please note: I am ignoring the disk based replication and recovery on purpose because the scope is truly HA where quick system availability after an incidence is most important. That certainly again feels like a good option for DR.
Now coming to the question:
Can someone share any insights on how you have setup HA for your scale-out systems? What do you like about it and what you think is difficult to operate with it?