Veritas Storage Foundation 5.1 SP1 for Oracle RAC Administrator"s Guide (5900-1512, April 2011)

Oracle Clusterware/Grid Infrastructure
Oracle Clusterware/Grid Infrastructure manages Oracle cluster-related functions
including membership, group services, global resource management, and
databases. Oracle Clusterware/Grid Infrastructure is required for every Oracle
RAC instance.
Oracle Clusterware/Grid Infrastructure requires the following major components:
■ A cluster interconnect that allows for cluster communications
■ A private virtual IP address for cluster communications over the interconnect
■ A public virtual IP address for client connections
■ For Oracle 11g Release 2, a public IP address as a Single Client Access Name
(SCAN) address on the Domain Name Server (DNS) for round robin resolution
to three addresses (recommended) or at least one address
■ Shared storage accessible by each node
Co-existence with VCS
Oracle Clusterware/Grid Infrastructure supports co-existence with vendor
clusterwares such as Veritas Cluster Server. When you install Oracle
Clusterware/Grid Infrastructure on an SF Oracle RAC cluster, Oracle
Clusterware//Grid Infrastructure detects the presence of VCS by checking the
presence of the Veritas membership module (VCSMM) library. It obtains the list
of nodes in the cluster from the VCSMM library at the time of installation.
When a node fails to respond across the interconnect, Oracle Clusterware/Grid
Infrastructure waits before evicting another node from the cluster. This wait-time
is defined by the CSS miss-count value. Oracle Clusterware/Grid Infrastructure
sets the CSS miss-count parameter to a larger value (600 seconds) in the presence
of VCS. This value is much higher than the LLT peer inactivity timeout interval.
Thus, in the event of a network split-brain, the two clusterwares, VCS and Oracle
Clusterware/Grid Infrastructure, do not interfere with each other’s decisions on
which nodes remain in the cluster. Veritas I/O fencing is allowed to decide on the
surviving nodes first, followed by Oracle Clusterware/Grid Infrastructure.
VCS uses LLT for communicating between cluster nodes over private interconnects
while Oracle Clusterware/Grid Infrastructure uses private IP addresses configured
over the private interconnects to communicate between the cluster nodes. To
coordinate membership changes between VCS and Oracle Clusterware/Grid
Infrastructure, it is important to configure the Oracle Clusterware/Grid
Infrastructure private IP address over the network interfaces used by LLT. VCS
uses the CSSD agent to start, stop, and monitor Oracle Clusterware/Grid
Infrastructure. The CSSD agent ensures that the OCR, the voting disk, and the
private IP address resources required by Oracle Clusterware/Grid Infrastructure
39Overview of Veritas Storage Foundation for Oracle RAC
Component products and processes of SF Oracle RAC