Dynamically Tunable Parameters in HP-UX 11i

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troubleshooting
Even with the best of intentions, it is possible to make a tunable value change that
degrades system performance. Such degradations may be immediately apparent, or
they may take some time to become noticeable. It is critically important that records
be kept of all tunable value changes, so that they can be reversed if needed.
Dynamic tunable changes are automatically recorded to syslog and to the Kernel
Logging subsystem. However, there is no automatic recording of static or automatic
changes to tunable values.
When a performance problem becomes apparent, any recent tunable value changes
should be considered suspect. Consider reversing those changes to see if the
performance problem disappears.
In a worst case scenario, a bad tunable value could result in a system that will not boot.
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In these cases, you should attempt to boot the previously working kernel, which is often
stored at /stand/vmunix.prev. You can then reverse the bad tunable change and
rebuild the offending kernel.
feedback
HP is very interested in feedback on the system tuning process and how it can
be improved. We particularly value suggestions about:
• The most useful form of future tuning documentation
• Which static tunables should be made dynamic soonest
• Which tunables should be made automatic, and with what tuning algorithm
Please send any such suggestions via e-mail to [e-mail].
We regret, due to the expected volume of feedback, that we will be unable to respond
personally to each suggestion. They will nonetheless be very valuable data for us as
we progress in improving HP-UX system tuning.
Please do not use the e-mail address above for bug reports, business escalations, hot
sites, etc. Contact your normal HP support channels for those issues so that they can
be handled as quickly as possible.
conclusion
• HP-UX 11i includes several ways of modifying kernel parameters dynamically—that is,
without rebooting. With dynamically tunable kernel parameters, users can tune their
systems without bringing down the system or sacrificing availability.
for more
information
Looking for more information about HP-UX 11i? Visit these Web sites:
• docs.hp.com
• www.hp.com/go/hpux
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HP strives to avoid operations that can result in an unbootable system. Unfortunately, we cannot avoid all such possibilities while still maintaining the
flexibility demanded by our customer base.