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 1 21

Dialog Instance packages provide high availability and flexibility at the

same time. The system becomes more robust using Dialog Instance

packages. The virtualization allows to move the instances manually

between the cluster hosts on demand.

Figure 1-2 Failover Node with Application Server package

Figure 1-2 illustrates a common configuration with the adoptive node

running as a Dialog Server during normal operation. Node1 and node2

have equal computing power and the load is evenly distributed between

the combination of database and Central Instance on node1 and the

additional Dialog Instance on node2. All software services provided by

the Dialog Instance are also configured as part of the Central Instance. If

node1 fails, the Dialog Instance package will be shut down during

failover of the (dbciSID) package. This is similar to a one-package setup

without Dialog Instance packaging. The advantage of this setup is, that

after repair of node1, the Dialog Instance package can just be restarted

on node1 instead of node2. This saves downtime that would otherwise be

dbciSID

dNRSID

1 DBCI failover

triggers Dialog

Instance package

utdown

2 Manual Dialog Instance

package restart