Managing Serviceguard Extension for SAP, December 2007

Understanding Serviceguard Extension for SAP
Designing SGeSAP Cluster Scenarios
Chapter 122
Some Application Server installations automatically install more than
one Central Instance at a time. E.g. a SAP Exchange Infrastructure 3.0
installation creates a DVEBMGS instance as well as a System Central
Service SCS instance using different Instance Numbers.
This SCS instance is technically identical with an ASCS instance, but it
delivers its services to the J2EE Engines instead of the ABAP Engines of
the Application Server.
NOTE SCS Instances are clustered with the package type jci. The naming
reflects that the SCS Instance delivers the critical Central Instance
Services for the Java portion of the Application Server.
A one-package installation for the SAP Exchange Infrastructure would
need to include three mission-critical components: the database, the
Central Instance for ABAP and the SCS Instance for JAVA. The package
would now be called dbcijciSID.
It is allowed to create cijciSID packages that just fail over SAP
software excluding the database which might be secured with different
means.
It is also possible to split a DVEBMGS instance into an ASCS and a Dialog
Instance. This process is described later in this document. As a result, a
single SAP System may have a SCS and an ASCS Instance at the same
time. SAP Application Server 7.0 provides installation options that
provides this combination of SCS and ASCS out of the box.