Install guide

Chapter 4. RAC/GFS Cluster Configuration

This chapter provides information on a configuring RAC/GFS cluster. For information on configuring a

cold failover HA cluster, see Chapter 5, Cold Failover Cluster Configuration.

Preparing a cluster for RAC requires additional package installation and configuration. Deploying Oracle

RAC on a certified GFS cluster requires additional software and configuration. T he aim of this section is

to demonstrate these scenarios.

Oracle RAC is a shared-disk option of Enterprise Edition that requires another Oracle product

(Clusterware) to be installed as well. T his complicates the Red Hat Cluster Suite install, as there are

now 2 independent clustering layers running simultaneously on the cluster. Oracle requires that

Clusterware (CRS) be installed on top of Red Hat Cluster Suite, and this will be the chapter’s focus. The

chapter assumes that the user can install CRS (as well as the RDBMS).

All Oracle database files can reside on GFS clustered volumes, except Oracle Clusterware product files

(ORA_CRS_HOME). T he Oracle RDBMS product files (ORACLE_HOME) can be installed on shared GFS

volumes, although Context Dependent Pathnames (CDPN) will be required for some ORACLE_HOME

directories.

4.1. Oracle Clusterware

Oracle Clusterware is a stand-alone cluster layer that Oracle provides for use with the RAC option. CRS

mimics all the functionality of Red Hat Cluster Suite, but must be tuned so as to not interfere with Red

Hat Cluster Suite’s ability to manage the cluster (and the GFS clustered file systems).

CRS requires a set of dedicated LUNs (that were allocated and configured for use with Multipath).

Starting with 11gR1, the helper LUNS no longer need to be raw devices, but can be standard block

devices. The inodes in the /dev/mapper file can now be used directly for the CRS Cluster Registry

(OCR) and quorum (VOTE) files.

Oracle CRS installation permits external redundancy and internal redundancy. T he external option

assumes the storage array is responsible for their protection. In this installation option, only one copy of

OCR and one copy of VOTE are allocated. In the internal redundancy configuration, Oracle creates two

OCR files, organized as a simple RAID1 mirror, and generates three quorum VOT E files. The number of

VOTE files can be higher, providing it is a prime number of files. Most installations choose three VOT E

files, and most installations choose internal redundancy. CRS is certified for use in both internal and

external redundancy.

Oracle CSS network services must be configured, and then set with sufficiently high timeouts to insure

that only Red Hat Cluster Suite is responsible for heartbeat and fencing. T hese values must be set, or

the configuration will not be supported.

CSS T imeout should be set to at least 300 seconds to 500 seconds. CSS Disk T imeout should be set

to 500 seconds.

Tip

Oracle cluster nodes are usually set to reboot and automatically re-enter the cluster. If the nodes

should remain fenced, then the option="off" value in the fence section of the

cluster.conf file can be set to ensure nodes are manually restarted. (The option value can

be set to "reboot", "on", or "off"; by default, the value is "reboot".)

Red Hat Enterprise Linux 5 Configuration Example - Oracle HA on Cluster Suite