Is it better to have 1) or 2) ?

1) one public network for both HADR replication and client connections
2) two networks - private for HADR replication and public for client connections

2 is best. I have been using a separate private network (crossover cable without switch is perfectly fine) for HADR since DB2 8.2 FP9. Dale McInnis, Senior Technical Development Manager, IBM, confirmed this approach at May IDUG meeting.

Do you know if option 2 is selected only for performance reasons?

And do you have Dale's HA presentation from May IDUG?

Dale was available so I got it from him. Thx.

I do it mostly for performance, but it also has the added benefit of being able to do a takeover without force even if the public network (or NIC) is down on one of the servers.

Thank you .