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Former Member

SAP Cluster(HA) installation


We are going to install new SAP system with High availability. I gone through the installation manual about HA but i did'nt get the solution. My question is, In node A we will be installing the Central instance. whether i need to install CI in Node B ? or i need to install Dailog instance only. If I install dialog instance in node B, how the Failover cluster will work with JAVA because it is going to have dispatcher and server0. Without CI in Node B it won't have java up and running because it depend on CI.



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    Former Member
    Sep 22, 2008 at 05:33 AM

    Hi John,

    In NWAS 700, Message Service and Enqueue Service which previously were offered my CI are separated from CI as SCS (For Java) and ASCS (For ABAP).

    And hence as per my understanding of NWAS 700 architecture, with above separation of (A)SCS there is no difference between CI (Central Instance) and DI (Dialog Instance).

    Hence, your Single point of failure is (A)SCS and not CI anymore.

    So, you need to install

    1)(A)SCS and CI on primary node.

    2) DI on secondary node.

    3) Enable switching of (A)SCS from primary to secondary. (No CI switching required)

    With this explanation again go through "Planning Guide Technical Infrastructure Guide - SAP NetWeaveru2122 70".

    Hope this helps.


    Nirav Shah.

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    • Former Member

      Thanks for your reply. But when we are doing cluster failover from Node A to Node B, the java is working in only one side that means in node B only because, we are having same instance number in central and DI instance. How to make work java in both the sides?