Managing Serviceguard Extension for SAP on Linux (IA64 Integrity and x86_64), February 2008

Understanding Serviceguard Extension for SAP on Linux
Clustering Stand-Alone J2EE Components
Chapter 122
necessary caused by a fail back of the (dbciSID) package. The two
instances can be separated to different machines without impacting the
production environment negatively. It should be noted that for this
scenario with just two hosts there is no requirement to enable automatic
failover for the Dialog Instance package
Handling of Redundant Dialog Instances
Non-critical SAP WAS ABAP Application Servers can be run on HP-UX,
SUSE or RedHat Linux application server hosts. These hosts do not need
to be part of the Serviceguard cluster. Even if the additional SAP WAS
services are run on nodes in the Serviceguard cluster, they are not
necessarily protected by Serviceguard packages. A combination of
Windows/Linux application servers is technically possible but additional
software is required to access Linux file systems or Unix-like remote
shells from the Windows system.
All non-packaged instance are called Additional Dialog Instances or
sometimes synonymously Additional SAP Application Servers to
distinguish them from mission-critical Dialog Instances. An additional
Dialog Instance that runs on a cluster node is called an Internal Dialog
Instance. External Dialog Instances run on HP-UX or Linux hosts that
are not part of the cluster.
Even if Dialog Instances are external to the cluster, they may be affected
by package startup and shutdown. For convenience, non-critical Dialog
Instances can be started and stopped with any Serviceguard Extension
for SAP on Linux package that secures critical components. Some SAP
applications require the whole set of Dialog Instances to be restarted
during failover of the Central Instance package. This can also be done
with Serviceguard Extension for SAP on Linux means. Dialog Instances
can be marked to be of minor importance. They will then be shut down, if
a critical component fails over to the host they run on in order to free up
resources for the non-redundant packaged components.
Additional Dialog Instances never get reflected in package names.
NOTE Declaring non-critical Dialog Instances in a package configuration
doesn’t add them to the components that are secured by the package. The
package won’t react to any error conditions of these additional instances.
The concept is distinct from the Dialog Instance packages that was
explained in the previous section.