HP OpenVMS 8.x manual General Notes About Modifying System Parameters

3.HP recommends that you run AUTOGEN from the SAVPARAMS phase through the TESTFILES phase weekly thereafter until the system stabilizes (that is, until AUTOGEN finds nothing that needs to be adjusted). Make sure you run AUTOGEN when your system is running under a typical workload. Examine AGEN$PARAMS.REPORT to determine the need for additional changes.

IMPORTANT: If you start AUTOGEN without specifying the execution-mode parameter (FEEDBACK, NOFEEDBACK, or CHECK_FEEDBACK), AUTOGEN uses the feedback information in its calculations. However, if the feedback information reflects system up time of less than 24 hours, or if the feedback information is more than 30 days old, AUTOGEN includes warnings in the AGEN$PARAMS.REPORT file to alert you to potential problems with the feedback data. If you wrongly assume the feedback is valid, the parameter settings might vary significantly from your expectations.

If you specify FEEDBACK (or NOFEEDBACK), AUTOGEN uses (or does not use) the feedback regardless of the data’s reliability. AUTOGEN proceeds through the SETPARAMS phase (if you specified SETPARAMS, SHUTDOWN, or REBOOT as the end phase) and sets system parameters to the values it computed.

If you specify CHECK_FEEDBACK, AUTOGEN checks the validity of the feedback data. If AUTOGEN determines the feedback is suspect, then AUTOGEN ignores the feedback when computing parameter values. It stops at the TESTFILES phase and issues a warning in the report that parameters have not been changed. You must read the report and decide whether the calculated values are acceptable. You can either use them (by running the AUTOGEN SETPARAMS phase) or rerun AUTOGEN with valid feedback data.

4.After the system has stabilized, HP recommends that you run AUTOGEN at least monthly to save feedback information for future use. Use the following command:

$ @SYS$UPDATE:AUTOGEN SAVPARAMS

If you do not maintain current feedback information for AUTOGEN, you will not have the needed information the next time you upgrade your system. As a result, you may have to reboot and rerun AUTOGEN several times to make your upgraded system operational.

For more information about running AUTOGEN, see the HP OpenVMS System Manager's Manual, Volume 2: Tuning, Monitoring, and Complex Systems.

7.23 Modifying System Parameters

Based on your examination of AGEN$PARAMS.REPORT, you might need to modify parameter values in MODPARAMS.DAT. Read the notes in Section 7.23.1 (page 145). These notes apply to modifications being made after a new installation and after an upgrade. If you are modifying system parameters after an upgrade, also see Section 7.23.2 (page 146).

7.23.1 General Notes About Modifying System Parameters

When modifying system parameters, note the following:

•In general, let AUTOGEN calculate system parameters. You can hardcode values (such as GBLPAGES=value), but doing so overrides AUTOGEN and might not allow it to set an optimal value based on observed usage.

•Whenever possible, use MIN_parameter values (such as MIN_GBLPAGES) to set the minimum value that can be set for a parameter by AUTOGEN. AUTOGEN increases the value if necessary. It also adjusts related parameters unless they are hardcoded, in which case information is provided in the AGEN$PARAMS.REPORT file. Use MAX_parameter values to set a maximum value when it is necessary to limit a parameter to a known maximum value (this is rarely necessary).

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