Overview

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High Availability of Servers in a Cluster across Data Centers

Ingredients

We had to set up a cluster of Universal Messaging nodes across Data Centers so that we ensure the high availability in case of a server crash either due to disaster or due to any issues on one of the nodes of the cluster. Universal Messaging is the messaging back-bone from Software A G Integration Product Suite. Same can be applicable for any server which is available for its clients to connect with our without the load balancer.

 

Step-by-step

  1. 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.

  2. 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.

  3. 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.

  4. Client Connections

    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 

    https://um1:port,um2:port,um3:port,um4:port

    Which ever server is available to consume sessions, the request will be accepted by that server.

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