Planning your storage and performance requirements on z/OS

You must set realistic and achievable storage, and performance goals for your IBM® MQ system. Use this topic help you understand the factors which affect storage, and performance.

This topic contains information about the storage and performance requirements for IBM MQ for z/OS®. It contains the following sections:

See, Where to find more information about storage and performance requirements for more information.

z/OS performance options for IBM MQ

With workload management, you define performance goals and assign a business importance to each goal. You define the goals for work in business terms, and the system decides how much resource, such as processor and storage, should be given to the work to meet its goal. Workload management controls the dispatching priority based on the goals you supply. Workload management raises or lowers the priority as needed to meet the specified goal. Thus, you need not fine-tune the exact priorities of every piece of work in the system and can focus instead on business objectives.

The three kinds of goals are:

Response time: How quickly you want the work to be processed
Execution velocity: How fast the work should be run when ready, without being delayed for processor, storage, I/O access, and queue delay
Discretionary: A category for low priority work for which there are no performance goals

Response time goals are appropriate for end-user applications. For example, CICS® users might set workload goals as response time goals. For IBM MQ address spaces, velocity goals are more appropriate. A small amount of the work done in the queue manager is counted toward this velocity goal but this work is critical for performance. Most of the work done by the queue manager counts toward the performance goal of the end-user application. Most of the work done by the channel initiator address space counts toward its own velocity goal. The receiving and sending of IBM MQ messages, which the channel initiator accomplishes, is typically important for the performance of business applications using them.

Determining z/OS workload management importance and velocity goals

See Determining z/OS workload management importance for more information.

Library storage

You must allocate storage for the product libraries. The exact figures depend on your configuration, but an estimate of the space required by the distribution libraries is 80 MB. The target libraries require about 72 MB. Additionally, you require space for the SMP/E libraries.

The target libraries used by IBM MQ for z/OS use PDS or PDSE formats. Ensure that any PDSE target libraries are not shared outside a sysplex. For more information about the required libraries and their sizes and the required format, see the Program Directory for WebSphere® MQ for z/OS. For download links for the Program Directories, see IBM MQ for z/OS Program Directory PDF files.

System LX usage

Each defined IBM MQ subsystem reserves one system linkage index (LX) at IPL time, and a number of non-system linkage indexes when the queue manager is started. The system linkage index is reused when the queue manager is stopped and restarted. Similarly, distributed queuing reserves one non-system linkage index. In the unlikely event of your z/OS system having inadequate system LXs defined, you might need to take these reserved system LXs into account.