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

1. SAP self-controlled using High Availability polling with Replication Instances on each cluster
node(active/passive).
2. Completely High Availability failover solution controlled with one virtualized Replication
Instance per Enqueue.
SGeSAP implements the second concept and avoids costly polling and complex data exchange
between SAP and the High Availability cluster software.
There are several SAP profile parameters that are related to the self-controlled approach. Most of
these parameters have names that start with the string enque/enrep/hafunc_. They will not
have any effect in SGeSAP clusters.
Example 4: Realization of the SAP-recommended SPOF isolation
SAP offers a formal HA cluster API certification for Netweaver 7.3x and above. SGeSAP implements
the certification requirements as specified by SAP. The approach requires isolating the SAP Central
Service software SPOFs in packages separate from non-SAP software packages like NFS package
and database package. The obvious advantage of this approach is that a failing software
component never causes a failover of still correctly running software that could be configured in
the same package.
Figure 6 Visualization of the Serviceguard cluster layout for SAP certification
Correctly set up clusters of this type are capable to provide the highest level of availability that is
technically possible. SGeSAP provides tools to master the complexity of SAP-recommended cluster
configurations.
NOTE: SGeSAP provides an easy deployment functionality (see deploysappkgs(1)) that
generates all required package configuration files for a SAP System. The tool has an option that
allows single-step creation of configuration files that are compliant with the SAP certification
requirements. This minimizes the likelihood of running mal-configured systems.
Example 5: Dedicated failover host
More complicated clusters that consolidate a couple of SAP applications often have a dedicated
failover server. While each SAP application has its own set of primary nodes, there is no need to
also provide a failover node for each of these servers. Instead, there is one commonly shared
secondary node that is capable of replacing any single failed primary node. Often, some or all
of the primary nodes are partitions of a large server.
Example 4: Realization of the SAP-recommended SPOF isolation 15