Installation and Upgrade Guide

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).
7.23 Modifying System Parameters 145