14
Oracle9i Real Application Clusters

This chapter provides guidelines for configuring Oracle9i Real Application Clusters after installing Oracle9i for OS/390. The following topics are included:

Overview

With the Oracle9i Real Application Clusters option, separate Oracle9i for OS/390 instances run simultaneously on one or more nodes (OS/390 images) and share a single physical database.

It is important to note that the OS/390 implementation follows the Oracle9i Real Application Clusters design guidelines. The only difference is the use of OS/390 filetypes. For more information, refer to the Oracle9i Real Application Clusters Book Set.

Oracle9i Real Application Clusters has the following characteristics:

One or more instances of Oracle9i Real Application Clusters can be started on a given node in the parallel sysplex.
Each instance has a separate SGA and set of background processes.
All instances share the same data files and control files of a given database.
All instances can execute transactions concurrently against the same database and each instance can have multiple users executing transactions.
Row level locking is preserved across the instances.

Applications accessing the database can run on the same nodes as multiple instances of Oracle9i Real Application Clusters, or on separate nodes of a parallel sysplex, or on distributed systems using the client/server architecture. Oracle9i Real Application Clusters can be part of a distributed database system. Distributed transactions access the data in a remote database in the same way, regardless of whether the data files are owned by an Oracle9i for OS/390 server (in exclusive mode) or an Oracle9i Real Application Clusters instance (in exclusive or parallel mode).

Other non-Oracle workload can run on each node of the sysplex or you can dedicate the entire sysplex or part of the sysplex to the Oracle server. For example, an Oracle9i Real Application Clusters instance and its applications might occupy three nodes of a five-node sysplex, while the other two nodes are used for non-Oracle applications.

Refer to the Oracle9i Real Application Clusters Book Set for more information about the Oracle9i Real Application Clusters environment. Refer to the concepts in the Oracle9i Real Application Clusters Book Set, especially the discussions on compatibility issues, restrictions, and database design guidelines.

Setting Up Real Application Clusters

The following steps describe important tasks you must perform when setting up an Oracle9i Real Application Clusters system, but they do not include all the tasks you might need to do for your site. Before performing these steps, review the concepts manual in the Oracle9i Real Application Clusters Book Set for more information.

Checklist for Setting Up Oracle9i Real Application Clusters:

Review and set options in the CREATE DATABASE statement
Set up additional threads of redo log files and rollback segments
Share all non-VSAM data sets
Set up the common OSDI parameters
Set up the common Oracle9i Real Application Clusters initialization parameters
Set up the instance-specific Oracle9i Real Application Clusters initialization parameters
Create the startup JCL

Step 1: Review and Set Options in the CREATE DATABASE Statement

Review and set the following options to allow multiple instances of Oracle9i Real Application Clusters to function properly. For a complete description of the CREATE DATABASE and ALTER DATABASE statements and options, refer to the Oracle9i Database Administrator's Guide and the Oracle9i SQL Reference.

MAXDATAFILES

The MAXDATAFILES option of CREATE DATABASE determines the number of data files a database can have. With Oracle9i Real Application Clusters, databases tend to have more data files and log files than an exclusive mounted database.

MAXINSTANCES

The MAXINSTANCES option of CREATE DATABASE limits the number of instances that can access a database concurrently. The default value for this option under OS/390 is 15. Set MAXINSTANCES to a value greater than the maximum number of instances you expect to run concurrently.

MAXLOGFILE 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 number of copies per group. Set MAXLOGFILES to the maximum number of instances you plan to run concurrently multiplied by the maximum anticipated number of groups per thread.

MAXLOGHISTORY

The MAXLOGHISTORY option of CREATE DATABASE specifies the maximum number of redo log files that can be recorded in the log history of the control file. The log history is used for automatic media recovery of Oracle9i Real Application Clusters.

For Oracle9i Real Application Clusters, set MAXLOGHISTORY to a large value, such as 100. The control file can then store information about this number of redo log files. When the log history exceeds this limit, the Oracle server overwrites the oldest entries in the log history. The default for MAXLOGHISTORY is 0 (zero), which disables log history.

Step 2: Set Up Additional Threads of Redo Log Files and Rollback Segments

Each Oracle9i Real Application Clusters instance requires its own redo log threads and rollback segments. Refer to the concepts manual of the Oracle9i Real Application Clusters Book Set for how to plan, create, and assign threads of redo and rollback segments to each instance.

Step 3: Share All Non-VSAM Data Sets

Because non-VSAM data sets will be used by multiple instances, ensure that the data sets used in the startup JCL of Oracle9i Real Application Clusters instances are specified with a DISP=SHR JCL parameter.

Step 4: Set Up the Database Region Parameters

Review and modify the OSDI database region parameters that apply to individual Oracle9i instances in one of the members of PARMLIB (for example, sidPARM, where sid is the database service identifier). OSDI database region parameters are described in "Database Region Parameters". These parameters are required to start individual Oracle9i instances. There are no Oracle9i Real Application Clusters-specific database region parameters.

Step 5: Set Up the Common Oracle9i Real Application Clusters Initialization Parameters

Review and modify the Oracle9i Real Application Clusters initialization parameters that apply to all instances in the sidINIT member of PARMLIB. The sidINIT member might also contain other parameters which are not directly applicable to Oracle9i Real Application Clusters but apply to all instances. For a complete list of parameters common or identical across all instances, refer to the Oracle9i Real Application Clusters Book Set.

Step 6: Set Up the Instance-specific Oracle9i Real Application Clusters Initialization Parameters

Create the Oracle9i Real Application Clusters initialization parameters that must be unique for each instance in a new member of PARMLIB. You may create as many of these members for as many instances as you plan to run mounting the same database. Each of these members also should specify the common initialization parameter file using the IFILE parameter.

Alternately all parameters can be specified in one member of PARMLIB. For syntax and notation required for using one initialization parameter file, please refer to the Oracle9i Real Application Clusters Book Set.

At a minimum, the INSTANCE_NUMBER, INSTANCE_NAME, and THREAD parameters are recommended for each instance.

Step 7: Operating an OSDI Database Service

Each instance of Oracle9i Real Application Clusters executes in a manner similar to a single OSDI-based database service. For more information, refer to Chapter 3, "Configuring a Database Service and Creating a New Database" and Chapter 5, "Operating a Database Service".

Before starting or stopping Oracle9i Real Application Clusters instances or doing backup and recovery operations, refer to the information about these topics in the Oracle9i Real Application Clusters Book Set.

Cross System Communication Facility (XCF)

Oracle9i Real Application Clusters requires the Cross System Communication Facility, commonly known as XCF. For more information about configuring XCF, please refer to the IBM document Setting Up a Sysplex, GC28-1779.

OS/390 Resource Name Usage

Oracle9i Real Application Clusters instances will, by default, make use of the following OS/390 resource names. If these names conflict with other software on your system and this cannot be changed, contact Oracle Worldwide Support for assistance.

XCF Group Names

Each instance will create and join XCF groups with names of the format Onnnxxxx, where nnn is an internally generated 3 character alphanumeric string to uniquely identify a cluster, and xxxx is a 4 character alphanumeric string to identify the type of XCF group. The following is an example using XCF names for the first Oracle9i Real Application Clusters instance:

XCF group for IPC Messages	: O001ORAM
XCF group for Node Monitor	: O001ORAN
Oracle Groups			: O001Gmmm

In the above example, the mmm are Oracle group numbers and are assigned serially.

OS/390 ENQ Names

Each instance will also take out global (sysplex-wide) enqueues on resources with names in the format:

Qname : OnnnORAG

where Qname is the queue name to be used for ENQs used by this cluster.

Rname : OnnnGxxx#yyy....yyy

where Rname is the resource name used by ENQs consisting of xxx (a three character alphanumeric string) and yyy...yyy (a variable length alphanumeric string, up to 18 characters).

For example, for the first Oracle9i Real Application Clusters instance with the database name ORACLE9I, the following name will be used:

O0001ORAG.O001G001#DBORACLE9I

14 Oracle9i Real Application Clusters