Monitoring system resources by using RMF

You can monitor system resources to detect constraints for processor, I/O, and storage resources.

About this task

You can use the information that you gather for the following purposes to:
  • Determine how resources, such as processor, I/O, and stage, are consumed in the system.
  • Analyzing processor, I/O, and paging rates to detect bottlenecks in the system.
  • Detect changes in the use of system resources over time, for comparable periods.

The following figure shows an example of a suggested system resources report.

Figure 1. User-created system resources report
                          SYSTEM RESOURCES REPORT         DATE xx/xx/xx
                                                          FROM xx:xx:xx
                                                          TO xx:xx:xx
 
 TOTAL CPU Busy        74.3 %
 
   Db2 & IRLM           9.3 %
   IMS/CICS            45.3 %
   QMF Users            8.2 %
   Db2 Batch & Util     2.3 %
   OTHERS               9.2 %
 
   SYSTEM AVAILABLE    98.0 %
 
 TOTAL I/Os/sec.       75.5
 
 TOTAL Paging/sec.      6.8
                              Short          Medium        Long
                              Transaction    Transaction   Transaction
 
 Average Response Time        3.2 secs       8.6 secs      15.0 secs
 
 MAJOR CHANGES:
               Db2 application DEST07 moved to production

The RMF reports used to produce the information in the preceding figure were:

  • The RMF CPU activity report, which lists TOTAL CPU busy and the TOTAL I/Os per second.
  • RMF paging activity report, which lists the TOTAL paging rate per second for real storage.
  • The RMF workload activity report, which is used to estimate where resources are spent. Each address space or group of address spaces to be reported on separately must have different SRM reporting or performance groups. The following SRM reporting groups are considered:
    • Db2 address spaces:
      • Db2 database address space (ssnmDBM1)
      • Db2 system services address space (ssnmMSTR)
      • Distributed data facility (ssnmDIST)
      • IRLM (IRLMPROC)
    • IMS or CICS®
    • TSO-QMF
    • Db2 batch and utility jobs
    The CPU for each group is obtained using the ratio (A/B) × C, where:
    • A is the sum of CPU and service request block (SRB) service units for the specific group
    • B is the sum of CPU and SRB service units for all the groups
    • C is the total processor utilization.
    The CPU and SRB service units must have the same coefficient.

    You can use a similar approach for an I/O rate distribution.

MAJOR CHANGES shows the important environment changes, such as:

  • Db2 or any related software-level change
  • Db2 changes in the load module for system parameters
  • New applications put into production
  • Increase in the number of QMF users
  • Increase in batch and utility jobs
  • Hardware changes

MAJOR CHANGES is also useful for discovering the reason behind different monitoring results.