14 Oracle Real Application Clusters (Oracle RAC)

This chapter describes what is BS2000-specific for RAC. This chapter includes the following topics:

BS2000 prerequisites for Oracle RAC
Installation of Oracle RAC
Creation and Configuration of a Database
Restrictions

For more information, refer to Oracle Real Application Clusters documentation set.

BS2000 prerequisites for Oracle RAC

The following are the prerequisites for Oracle RAC:

An inter-process communication system between the nodes of a cluster
A clusterware
A shared file system.

The interprocess communication system enables Oracle to exchange messages and coordinate operations between the instances on the cluster, the clusterware specifies to Oracle, which node is part of the cluster, which is not, and prohibits dead nodes to interfere with the healthy ones. The shared file system gives access of the common database files to the instances on the different nodes of the cluster.

The interprocess communication (IPC) of Oracle RAC is based on the protocol UDP/IP of BS2000/OSD openNet Server.

HIPLEX MSCF delivers clusterware and shared file system on BS2000. You must run HIPLEX MSCF as an XCS, cross coupled system, with an XCS shared pubset. RAC cannot operate without these prerequisites.

For more information on HIPLEX MSCF, refer to the BS2000/OSD HIPLEX MSCF guide.

The generic Oracle Clusterware is not supported with RAC on BS2000/OSD. Consequently, Oracle Clusterware utilities such as SRVCTL or Cluster Verification Utility are not supported.

Refer to Oracle Clusterware and Oracle Real Application Clusters Administration and Deployment Guide for information about the generic Oracle RAC concepts.

Installation of Oracle RAC

Installation of Oracle RAC software is not different from the single instance BS2000 installation. Oracle RAC is a part of the Oracle Database 10g release 2 software and is implicitly installed when you install Oracle Database 10g.

It is important to install the Oracle software on an XCS shared pubset in order to have shared access to the Oracle Database software from different XCS nodes, that is, the default pubset of the installation user ID should be an XCS pubset.

The following steps must be performed for Oracle RAC installation:

Install clusterware
Configure shared disks
Install Oracle Database 10g Enterprise Edition and Oracle Real Application Cluster software
Create and configure the database

With an HIPLEX MSCF XCS cluster and an XCS shared pubset you implicitly get clusterware and shared disks with a cluster file system.

The usual single instance installation puts you at the end of step 3.

The fourth step is described in the next section.

Creation and Configuration of a Database

To avoid RAC process overhead for non-RAC instances on BS2000, an ORAENV parameter notifies Oracle if Oracle RAC should be switched on or off:

ENABLE_RAC=TRUE/FALSE

This parameter controls Oracle RAC operation on a BS2000 cluster. It does not replace INIT.ORA parameters, such as CLUSTER_DATABASE=TRUE. The meaning of all Oracle RAC related INIT.ORA parameters is unchanged. ENABLE_RAC=TRUE in ORAENV must be set as a prerequisite to use RAC on BS2000.

There is no Database Configuration Assistant on BS2000. You must create the database manually using SQL*Plus.

The next sections describe how to create and configure an Oracle database within an Oracle RAC configuration:

Placement of Files

The control file, the server parameter file, all data files and all (online and archive) redo log files have to be placed on a shared pubset so that all instances of an Oracle RAC configuration can access them.

Oracle recommends that you use a shared pubset as default pubset for the DBA user ID on each cluster node.

Options in the CREATE DATABASE Statement

The following options are available in the CREATE DATABASE statement:

MAXINSTANCES: The MAXINSTANCES option of CREATE DATABASE limits the number of instances that can access a database concurrently. For Oracle RAC, set MAXINSTANCES to a value greater than the maximum number of instances you expect to run concurrently.
MAXDATAFILES: The MAXDATAFILES option of CREATE DATABASE determines the number of data files a database can have. With Oracle RAC, databases tend to have more data files and log files than an exclusively mounted database.
MAXLOGFILES and MAXLOGMEMBERS: The MAXLOGFILES option of CREATE DATABASE specifies the maximum number of redo log groups that can be created for the database. The MAXLOGMEMBERS option specifies the maximum number of members or copies for each group. Set MAXLOGFILES to the maximum number of threads possible, multiplied by the maximum anticipated number of groups for each thread multiplied by MAXLOGMEMBERS for each group.
MAXLOGHISTORY: The MAXLOGHISTORY option of CREATE DATABASE specifies the maximum number of archived redo log files that can be recorded in the control file. For Oracle RAC, set MAXLOGHISTORY to a large value, such as 100.

If you have an existing database you can use the CREATE CONTROLFILE statement to change the value of these CREATE DATABASE options.

Additional Threads of Redo Log Files

Each instance in an Oracle RAC configuration has its own thread of online redo log files. Create a thread with at least two redo log groups for each instance and enable each thread so the instance can use it.

For creating additional threads of online redo log files you can use the ALTER DATABSE statement.

Additional Undo Tablespaces

Oracle strongly recommends that you use automatic undo management. This feature automatically manages undo space.

Each instance in an Oracle RAC configuration must have its own undo tablespace. So assign a separate undo tablespace to each instance.

Oracle RAC- related views

You must run the script CATCLUST.SQL to create RAC-related views and tables. You must have SYSDBA privileges to run the script.

Initialization Parameters

Refer to Oracle Clusterware and Oracle Real Application Clusters Administration and Deployment Guide to get detailed information about setting the initialization parameters for Oracle RAC.

There are some global parameters which must be identical on every instance. For example, on every instance of an Oracle RAC configuration you have to set the database to start in the cluster mode by specifying the following init.ora parameter:

CLUSTER_DATABASE=TRUE

There are other parameters which are specific for each instance of an Oracle RAC configuration. For example the THREAD, INSTANCE_NAME, and INSTANCE_NUMBER parameters must have unique values on all instances.

Creating Password Files

If you want to administer all instances of an Oracle RAC configuration remotely from one node of the cluster, you have to create password files for each instance using the ORAPWD utility.

Configuring Oracle Net Services

You have to configure Oracle Net Services on each node of the cluster by setting up the Oracle Net parameter files (LISTENER.ORA, TNSNAMES.ORA, SQLNET.ORA).

Restrictions

The following are the restrictions when using BS2000:

Administering RAC Instances

On BS2000 you cannot administer Oracle RAC Instances with Oracle Enterprise Manager or the SRVCTL-Utility of Oracle Cluster Ready Services. So you have to use SQL*Plus for the Administration of Oracle RAC instances.Refer to the Oracle Clusterware and Oracle Real Application Clusters Administration and Deployment Guide for more information about Oracle RAC administration with SQL*Plus.
Oracle Clusterware

Generic Oracle Clusterware is not supported on BS2000.

SRVCTL and Cluster Verification Utility are not supported.