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Control File Tuning: Implementation

In the previous sections you learned that you can use the DISPLAY IO and DISPLAY SERVICE commands to analyze control file cycle and transaction processing rates. You also learned that you could use the SETOPTION MODE, CYCLE, and INTERVAL parameters to increase or decrease CA MIM control file cycle rates on individual systems. In this section, you learn the procedures that you can use to tune control file access rates in your MIMplex.

  1. Although not mandatory, it is best to begin with CA MIM having the defaults of SETOPTION MODE=DEMAND, CYCLE=1, INTERVAL=1. Your current values for these CA MIM parameters can be determined by issuing the DISPLAY IO command on every system. If you find that you are not running with these defaults, then you can execute the SETOPTION command to change these parameters to their defaults.
  2. Issue DISPLAY IO=RESET and DISPLAY SERVICE=RESET to CA MIM on every system. This will re-initialize the performance statistics and will allow all CA MIM address spaces to begin accumulating statistics from the same starting point.
  3. Allow the statistics to accumulate for at least a 24-hour period. This lets CA MIM to acquire statistics for all shifts, and ideally includes your heaviest workload period.
  4. Issue the DISPLAY IO and DISPLAY SERVICE commands on all systems. Print the statistics.

    You will notice that the display data has two parts, one containing statistics since CA MIM startup, and the other containing statistics since last reset. You will want to use the statistics accumulated since the last reset command was issued.

    Analyze the statistics. Determine which systems, if any, need to be performing more control file cycles. Usually, control file access tuning involves increasing control file cycles only on one or two systems.

    Note: For help with interpreting this data, see Control File Tuning: Analysis in this chapter. If you would like assistance in analyzing your MIMplex statistics, contact CA MIM Technical Support.

  5. Issue a SETOPTION MODE, CYCLE, or INTERVAL command on the selected system to adjust control file access rates appropriate to your environment. The command SETOPTION INTERVAL=.1 provides a control file cycle rate of 10 accesses per second and is a safe starting point when it is desirable to increase the number of cycles on an inactive system. The SETOPTION CYCLE=1 should always used unless otherwise directed by CA MIM Technical Support.

    More information:

    Control File Tuning: Parameters

  6. Issue the commands DISPLAY IO=RESET and DISPLAY SERVICE=RESET to CA MIM on every system. This re-initializes the CA MIM performance statistics and lets CA MIM begin accumulating statistics reflecting the effects of your altered CA MIM tuning parameters.
  7. Allow the new statistics to accumulate for 24 hours.
  8. Issue the DISPLAY IO and DISPLAY SERVICE commands on all systems. Print the statistics. Then loop back to Step 5.
  9. Repeat Steps 5 - 9 until you have adjusted the CA MIM tuning parameters such that the DISPLAY IO and DISPLAY SERVICE data contains acceptable values for every system.
  10. Once you have achieved the desired results, you should make a permanent change to the MIMCMNDS member of the CA MIM parmlib. Using IFSYS/ENDIF statements you can ensure the desired SETOPTION MODE, CYCLE, AND INTERVAL values are defined for each systems.