Central instance and SAP instance

[former_member199632]

hello,

Im confusing with Central Instance (CI) and SAP instance (Application Instance)

According to my understanding, i think SAP instance is running on all the Aplication servers. (if having 4 Application servers, in all those servers, SAP instance is running concurrently)

But Central instance is running on 1 of the Application servers only.

- How will the SAP decides on which Application should run the central instance.

Will that CI change automatically time to time.... or do we need to allocate 1 Application server as CI server, when doing the installation.

Is there any relationship between Message server and Central instance.

Does CI contains message services and enqueue service...

plz help me to reslove these issues

Rgds,

Edited by: zerandib on Apr 25, 2010 10:45 AM

[Former Member]

How will the SAP decides on which Application should run the central instance.
Will that CI change automatically time to time.... or do we need to allocate 1 Application server as CI server, when doing the installation.

Usualy in non HA installation's central instance are located on it's own host. But in some HA installation's central instance can start's on any available application server host (for example in our HA are this configured).

P.S.

Is there any relationship between Message server and Central instance.

Does CI contains message services and enqueue service...

Try to read http://help.sap.com/saphelp_nw70ehp2/helpdata/en/47/fe7aa040e23c8be10000000a42189c/frameset.htm

Regards.