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

Figure 7 Dedicated failover server
SGeSAP Cluster
Dedicated Failover Server with
Replicated Enqueue
Failover paths from all
primary partitions to the
dedicated backup server
jdbscsC11
Node 1
dbascsC12
Node 2
ers00C11
ers10C12
ersnnCnn
Dialog Instances
dbscsCnn
Node 3
Shared Disks
Figure 7 (page 16) shows an example configuration. The dedicated failover host can serve many
purposes during normal operation. With the introduction of Replicated Enqueue Servers, it is a
good practice to consolidate a number of Replicated Enqueues on the dedicated failover host.
These replication units can be halted at any time without disrupting ongoing transactions for the
systems they belong to. They are sacrificed in emergency conditions when a failing database and
or Central Service Instance need the spare resources.
Dedicated NFS packages
Small clusters with only a few SGeSAP packages usually provide NFS by combining the NFS toolkit
package functionality with the SGeSAP packages that contain a database component. The NFS
toolkit is a separate product with a set of configuration and control files that must be customized
for the SGeSAP environment. It needs to be obtained separately. NFS is delivered in a distributed
fashion with each database package serving its own file systems. By consolidating this into one
package, all NFS serving capabilities can be removed from the database packages. In complex,
consolidated environments with several SGeSAP packages, it is of significant help to use one
dedicated NFS package instead of blending this into existing packages.
16 SAP cluster concepts