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

The coordination point server (CP server) is a software solution which runs
on a remote system or cluster. CP server provides arbitration functionality by
allowing the SF Oracle RAC cluster nodes to perform the following tasks:
■ Self-register to become a member of an active SF Oracle RAC cluster
(registered with CP server) with access to the data drives
■ Check which other nodes are registered as members of this activeSF Oracle
RAC cluster
■ Self-unregister from this active SF Oracle RAC cluster
■ Forcefully unregister other nodes (preempt) as members of this active SF
Oracle RAC cluster
In short, the CP server functions as another arbitration mechanism that
integrates within the existing I/O fencing module.
Note: With the CP server, the fencing arbitration logic still remains on the SF
Oracle RAC cluster.
Multiple SF Oracle RAC clusters running different operating systems can
simultaneously access the CP server. TCP/IP based communication is used
between the CP server and the SF Oracle RAC clusters.
About preferred fencing
The I/O fencing driver uses coordination points to prevent split-brain in a VCS
cluster. By default, the fencing driver favors the subcluster with maximum number
of nodes during the race for coordination points. With the preferred fencing
feature, you can specify how the fencing driver must determine the surviving
subcluster.
You can configure the preferred fencing policy using the cluster-level attribute
PreferredFencingPolicy as follows:
■ Enable system-based preferred fencing policy to give preference to high
capacity systems.
■ Enable group-based preferred fencing policy to give preference to service
groups for high priority applications.
■ Disable preferred fencing policy to use the default node count-based race
policy.
See “How preferred fencing works” on page 48.
See “Enabling or disabling the preferred fencing policy” on page 131.
47Overview of Veritas Storage Foundation for Oracle RAC
About preventing data corruption with I/O fencing