VERITAS Storage Foundation 4.1 for Oracle RAC HP Serviceguard Storage Management Suite Extracts, December 2005

What is RAC?
Operating System-Dependent Layer
Oracle RAC relies on several support services provided by Serviceguard. The important features
are cluster membership carried out by the cluster membership manager and inter-node
communication. The actual implementation of these functions is described later in this
chapter (see
“Storage Foundation for Oracle RAC OSD Layer Support” on page 12).
environment to transfer messages between instances.
Lock Management and Cache Fusion
Lock management coordinates access for multiple instances to the same data to maintain
data consistency and integrity. Oracle’s Cache Fusion provides memory-to-memory
transfers of data blocks between RAC instances; these transfers are faster than transfers
involving writing to and reading from disk across the cluster nodes.
Shared Disk Subsystems
RAC requires all nodes have simultaneous access to database storage. This requirement
gives multiple instances concurrent access to the same database.
Chapter 1, Overview: Storage Foundation for Oracle RAC 3