Using Serviceguard Extension for RAC, 6th Edition, April 2008

How Serviceguard Works with Oracle 9i RAC
Serviceguard provides the cluster framework for Oracle, a relational database product
in which multiple database instances run on different cluster nodes. A central component
of Real Application Clusters is the distributed lock manager (DLM), which provides
parallel cache management for database instances. Each node in a RAC cluster starts
an instance of the DLM process when the Oracle instance starts and the instances then
communicate with each other over the network.
Group Membership
The group membership service (GMS) is the means by which Oracle instances
communicate with the Serviceguard cluster software. GMS runs as a separate daemon
process that communicates with the cluster manager. This daemon is an HP component
known as cmgmsd.
The cluster manager starts up, monitors, and shuts down the cmgmsd. When an Oracle
instance starts, the instance registers itself with cmgmsd; thereafter, if an Oracle instance
fails, cmgmsd notifies other members of the same group to perform recovery. If cmgmsd
dies unexpectedly, Serviceguard will fail the node with a TOC (Transfer of Control).
Configuring Packages for Oracle RAC Instances
Oracle instances can be configured as packages with a single node in their node list.
NOTE: Packages that start and halt Oracle instances (called instance packages) do
not fail over from one node to another; they are single-node packages. You should
include only one NODE_NAME in the package ASCII configuration file. The AUTO_RUN
setting in the package configuration file will determine whether the RAC instance will
start up as the node joins the cluster. Your cluster may include RAC and non-RAC
packages in the same cluster.
Configuring Packages for Oracle Listeners
Oracle listeners can be configured as packages within the cluster (called listener
packages). Each node with a RAC instance can be configured with a listener package.
Listener packages are configured to automatically fail over from the original node to
an adoptive node. When the original node is restored, the listener package automatically
fails back to the original node.
In the listener package ASCII configuration file, the FAILBACK_POLICYis set to
AUTOMATIC. The SUBNET is a set of monitored subnets. The package can be set to
automatically startup with the AUTO_RUN setting.
Each RAC instance can be configured to be registered with listeners that are assigned
to handle client connections. The listener package script is configured to add the package
IP address and start the listener on the node.
Configuring Packages for Oracle RAC Instances 29