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 120
One can simulate this flexibility by installing Dialog Instances on every
host and activating them if required. This might be a feasible approach
for many purposes and saves the need to maintain virtual IP addresses
for each Dialog Instance. But there are ways that SAP users
unintentionally create additional short-term SPOFs during operation if
they reference a specific instance via its hostname. This could e.g. be
done during batch scheduling. With Dialog Instance packages, the
system becomes invulnerable against this type of user error.
Dialog Instance virtualization packages still provide high availability.
The system becomes more robust and flexible using Dialog Instance
packages.