Managing Serviceguard Extension for SAP on Integrity Linux, December 2005

Understanding Serviceguard Extension for SAP on Integrity Linux
Overview of SGeSAP on Integrity Linux
Chapter 110
Overview of SGeSAP on Integrity Linux
SAP environments allows a great amount of flexibility in setup and
configuration. The SGeSAP Integration Scripts preserve much of this
flexibility through the use of different configuration models:
• One-Package Configuration Model
• Two-Package Configuration Model
• Central NFS Configuration Model
One-Package Configuration Model
In a one-package configuration, both the database and central instance
run on the same node at all times and are configured in one Serviceguard
package, called a DBCI package. Other nodes in the Serviceguard cluster
function as backups for the primary node (on which the system runs
during normal operation).
During normal operation, backup nodes can be used as idle standby, or
various kinds of SAP instances like SAP central instances or application
servers, SAP development systems or SAP test systems. The shutdown
or restart of any number of application servers and SAP instances as
part of the package failover is supported. Multi-instance SAP systems
are allowed inside a cluster. The number of cluster nodes can be chosen
according to the current limitations of Serviceguard for Linux for
Integrity.
If the primary node fails, the database and the central instance fail over
and continue functioning on an failover node. The process of failover
results in downtime that can last several minutes, depending on the
work in progress when the failover takes place. The main portion of this
downtime is needed for the recovery of the database.
After failover, the system runs without any manual intervention needed.
Application servers belonging to the failover system can either stay up
or can be restarted during failover.