Install Servers across data centres
Install UM1 and UM2 instaces on machine1 and machine2 in Data Centre1.
Install UM3¬†and UM4 instaces on machine3 and machine4 in Data Centre2.
Cluster Set up
Log into Enterprise Manager tool (as shown in screen shot), and configure a 4 node cluster across all 4 instances of the UM Realm.
Dedicated communication card for inter node cluster communication
Request for dedicated interface card for the clusters to communication, this is a private network.
Set up the 4 nodes to communicate with each other using the dedicated port via this card.
The clients will hit the UM, using the regular application tcp/ip port.
Advantage of this is, cluster sync does not use the public network, its faster.
Plus any one node going down, in either of the data centers does not impact over all cluster healt.
Now configure the clients to connect to servers using one of the two following ways –
1) Put a load balancer on top of the 4 node cluster. Load balancer will send sessions to one of the available servers.
2) If the server works with a comma seperated URL, configure clients to work as¬†
Which ever server is available to consume sessions, the request will be accepted by that server.