Managing Serviceguard Extension for SAP Version A.06.00 for Linux, December 2012

Configuration restrictions
• It is not allowed to specify a single SGeSAP package with two database instances in it.
• It is not allowed to specify a single SGeSAP package with a Central Service Instance [A]SCS
and its Replication Instance ERS.
• Diagnostic Agent instances are not mandatory for SAP line-of-business processes, but they
become installed on the relocatable IP address of the corresponding instance and must move
with the relocatable IP address. They can be specified with module
sgesap/sapextinstance. An issue with the Diagnostic Agent during failover is thus not
considered as critical for the overall success of the failover operation. sgesap/sapinstance
must not be used for Diagnostic Agents.
• It is not a requirement to do so, but it can help to reduce the complexity of a cluster setup, if
SCS and ASCS are combined in a single package. Under these circumstances, it needs to be
considered that the failure of one of the two instances will also cause failover for the other
instance. This might be tolerable in those cases in which SAP replication instances are
configured (see below).
• sgesap/sapinstance packages can identify the state of a corresponding
sgesap/dbinstance package in the same cluster without the requirement of explicitly
configuring Serviceguard package dependencies. The information is for example used to
delay SAP instance package startups while the database is starting in a separate package,
but not yet ready to accept connections.
Example 1: Robust failover using the one package concept
In a one-package configuration, the database, NFS, and SAP SPOFs run on the same node at all
times and are configured in one SGeSAP package. Other nodes in the Serviceguard cluster function
as failover nodes for the primary node on which the system runs during normal operation.
Configuration restrictions 9