I have 3 OES2 SP1 servers running eDir 8.8.4 and would like to upgrade to the latest version available through yast online update. What's the proper procedure?

SRV1 holds the master replica, SRV2 holds a read/write and SRV3 does not hold any replicas.

Here's my understanding of it:
1) Apply the update on SRV1 restart nds then run "ndsconfig upgrade"
2) Apply update to SRV2 and restart nds
3) Apply update to SRV3 and restart nds

Is this correct, or do I need to run "ndsconfig upgrade" on each server?

Thank you.