Using Serviceguard Extension for RAC, 5th Edition, June 2007

Introduction to Serviceguard Extension for RAC
Overview of SGeRAC and Oracle 10g RAC
Chapter 1 23
Overview of SGeRAC and Oracle 10g RAC
Starting with Oracle 10g RAC, Oracle has bundled its own cluster
software. The initial release is called Oracle Cluster Ready Service
(CRS). CRS is used both as a generic term referring to the Oracle cluster
software and as a specific term referring to a component within the
Oracle clusters software. At subsequent release, Oracle generic CRS is
renamed to Oracle Clusterware. Oracle Clusterware is the generic term
referring to the Oracle Cluster Software.
The Oracle Cluster Software includes the following components: Cluster
Synchronization Services (CSS), Cluster Ready Service (CRS), and Event
Management (EVM).
CSS manages the Oracle cluster membership and provides its own group
membership service to RAC instances. When installed on a SGeRAC
cluster, CSS utilizes the group membership service provided by SGeRAC.
CRS manages Oracle's cluster resources based on configuration,
including start, stop, and monitor, and failover of the resources.
EVM publishes events generated by CRS and may run scripts when
certain events occur.
When installed on a SGeRAC cluster, both the Oracle cluster software
and RAC can continue to rely on the shared storage capability,
networking monitoring, as well as other capabilities provided through
Serviceguard and SGeRAC.
Oracle 10g RAC uses the following two subnets for cluster
communication purposes:
• CSS Heartbeat Network (CSS-HB): Oracle Clusterware running on
the various nodes of the cluster communicate among themselves
using this network.
• RAC Cluster Interconnect Network (RAC-IC): Database instances of
a database use this network to communicate among themselves.