Oracle® Database System Administration Guide
10g Release 1 (10.1) for IBM z/OS (OS/390)
Part No. B13526-01
With the Oracle Real Application Clusters option, separate Oracle Database for z/OS instances run simultaneously on one or more nodes (z/OS images) and share a single physical database.
It is important to note that the z/OS implementation follows the Oracle Real Application Clusters design guidelines. The only difference is the use of z/OS filetypes. For more information, refer to the Oracle Real Application Clusters Book Set.
Oracle Real Application Clusters has the following characteristics:
One or more instances of Oracle 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 Oracle Real Application Clusters, or on separate nodes of a parallel sysplex, or on distributed systems using the client/server architecture. Oracle 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 Oracle Database for z/OS server (in exclusive mode) or an Oracle Real Application Clusters instance (in exclusive or parallel mode).
Other non-Oracle workloads 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 Oracle 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 Oracle Real Application Clusters Book Set for more information about the Oracle Real Application Clusters environment. Refer to the concepts in the Oracle Real Application Clusters Book Set, especially the discussions on compatibility issues, restrictions, and database design guidelines.
The following steps describe important tasks you must perform when setting up an Oracle 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 Oracle Real Application Clusters Book Set for more information.
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 Oracle Real Application Clusters initialization parameters
Set up the instance-specific Oracle Real Application Clusters initialization parameters
Create the startup JCL
Review and set the following options to allow multiple instances of Oracle Real Application Clusters to function properly. For a complete description of the CREATE DATABASE and ALTER DATABASE statements and options, refer to the Oracle Database Administrator's Guide and the Oracle Database SQL Reference.
The MAXDATAFILES option of CREATE DATABASE determines the number of data files a database can have. With Oracle Real Application Clusters, databases tend to have more data files and log files than an exclusive mounted database.
The MAXINSTANCES option of CREATE DATABASE limits the number of instances that can access a database concurrently. The default value for this option under z/OS is 15. Set MAXINSTANCES to a value greater than the maximum number of instances you expect to run concurrently.
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.
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 Oracle Real Application Clusters.
For Oracle 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.
Each Oracle Real Application Clusters instance requires its own redo log threads and rollback segments. Refer to the concepts manual of the Oracle Real Application Clusters Book Set for how to plan, create, and assign threads of redo and rollback segments to each instance.
Because non-VSAM data sets will be used by multiple instances, ensure that the data sets used in the startup JCL of Oracle Real Application Clusters instances are specified with a DISP=SHR JCL parameter.
Review and modify the OSDI database region parameters that apply to individual Oracle Database for z/OS instances in one of the members of PARMLIB (for example,
sid is the database service identifier). OSDI database region parameters are described in "Database Region Parameters" in Chapter 3, "Configuring a Database Service and Creating a New Database". These parameters are required to start individual Oracle Database for z/OS instances. To enable Oracle Real Application Clusters, set the CLUSTER_ENABLE parameter to YES.
Review and modify the Oracle 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 Oracle Real Application Clusters but apply to all instances. For a complete list of parameters common or identical across all instances, refer to the Oracle Real Application Clusters Book Set.
init.ora parameter file,
_cluster_library=skgxn must be set.
Create the Oracle 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 Oracle Real Application Clusters Book Set.
At a minimum, the INSTANCE_NUMBER, INSTANCE_NAME, and THREAD parameters are recommended for each instance.
Each instance of Oracle 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 Oracle Real Application Clusters instances or doing backup and recovery operations, refer to the information about these topics in the Oracle Real Application Clusters Book Set.
Oracle Real Application Clusters requires the Cross System Communication Facility, commonly known as XCF. For more information about configuring XCF, refer to the IBM document MVS Setting Up a Sysplex.
Oracle Real Application Clusters instances will, by default, make use of the following z/OS 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 O
nnn is an internally generated three-character alphanumeric string to uniquely identify a cluster, and
xxxx is a four-character alphanumeric string to identify the type of XCF group. The following is an example using XCF names for the first Oracle 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.
Each instance will also take out global (sysplex-wide) enqueues on resources with names in the format:
Qname is the queue name to be used for ENQs used by this cluster.
Rname is the resource name used by ENQs consisting of
xxx (a three-character alphanumeric string) and
yyy (a variable length alphanumeric string, up to 18 characters).
For example, for the first Oracle Real Application Clusters instance with the database name ORACLE10, the following name will be used: