Part IV: DB2 Performance Monitoring

After you have established a DB2 environment and installed application systems that access that environment, it is imperative that the environment be monitored regularly to ensure optimal performance. The job of monitoring DB2 performance usually is performed by a database administrator, performance analyst, or system administrator.

Many factors contribute to the performance level achieved by DB2 applications. Unless an orderly and consistent approach to DB2 performance monitoring is implemented, an effective approach to tuning cannot be achieved and the performance of DB2 applications might fluctuate wildly from execution to execution.

Let's examine the traits of DB2 that make performance monitoring a crucial component of the DB2 environment. DB2 is an MVS subsystem composed of many intricate pieces. Each of these pieces is responsible for different performance-critical operations. In Chapters 10 and Chapter 11, you learned that DB2 itself is composed of several distinct address spaces that communicate with one another. You learned also about the features of the optimizer. Without a way to measure the relative performance of each of these pieces, it is impossible to gauge factors affecting the overall performance of DB2 applications, programs, and SQL statements.

In addition, DB2 applications regularly communicate with other MVS sub-systems, which also require routine performance monitoring. The capability to monitor MVS batch, CICS, IMS/TM, and TSO address spaces as well as other DB2 address spaces using distributed database capabilities is critical. Many factors influence not only the performance of DB2, but also the performance of these other MVS subsystems. It is important, therefore, to implement and follow a regular schedule of monitoring the performance of all the interacting components of the DB2 environment.

Part IV presents a methodical approach to the evaluation of DB2 performance. This section discusses the many elements that make up DB2 performance monitoring, including DB2 traces, IBM's DB2 performance monitor, and other DB2 and allied agent performance monitors. Remember, though, that this section covers the monitoring of DB2 performance. Methods of pinpointing potential performance problems are examined, but guidelines for correcting them are not covered until Part V, "DB2 Performance Tuning."

Defining DB2 Performance

You must have a firm definition of DB2 performance before you learn ways to monitor it. You can think of DB2 performance using the familiar concepts of supply and demand. Users demand information from DB2. DB2 supplies information to those requesting it. The rate at which DB2 supplies the demand for information can be termed DB2 performance.

Five factors influence DB2's performance: workload, throughput, resources, optimization, and contention.

Types of DB2 Performance Monitoring

There are many types of DB2 performance monitoring. It is wise to implement procedures for all different types of DB2 performance monitoring. If you do not monitor using all available methods, your environment has an exposure that might cause performance degradation that cannot be quickly diagnosed and corrected.

DB2 performance monitoring can be broken down into the following seven categories: