High Utilization

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Revision as of 00:01, 5 January 2008 by Snidelydev (Talk | contribs) (fixed typo re dbg commands)

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Draft High Utilization Wiki

Starting point for wiki article on diagnosing high utilization

High Utilization is a popular topic in the support forums (novell.support.netware.6x.abends-hangs, for instance, and this forum is mirrored in novell.support.open-enterprise-server.netware.abend-hangs; see also novell.support.netware.6x.administration-tools/novell.support.open-enterprise-server.netware.administration-tools). The 6x forums are also accessible under the OES forum folders: OES NW Abend Forum. For older systems, see NW5.x Abend Forum; the 4.x forums are nearby for those on an accelerated update path.

High utilization can keep a system administrator's phone or help desk busy, as users may experience delays in accessing files or print services or web pages.

Finding the Thread

Use the following techniques to find the thread (a unit of processor execution) that is the cause of the high utilization.

Use Monitor.nlm (tab to "next window", then select Kernel->Busiest Threads) or NRM (Diagnose Server->Profile/Debug->Profile CPU Execution by NLM) to see what is listed. If you're uncertain about the meaning of what you see, paste the output from one these tools into a posting in the support forums.

Note that threads listed as "server 09" and such are generally handling NCP requests from clients, so if such a thread is busiest, then check your workstations.


Hangs can either be a very uncooperative process tying up the processor in a way that escapes the CPU hog timer, or a hardware problem. The first check after finding you can't get a response at the console is to try to enter the (built-in) system debugger. If you're not familiar with how to do that, it involves the "4-finger salute" -- the 2 SHIFT keys, the ESC key, and an ALT key are all used together ("depressed at the same time", which sounds pretty gloomy). This is usually done with 2 hands -left hand for left SHIFT and ESC, right hand for right ALT and right SHIFT.

If you get a debugger prompt, you can then begin to try to see what was going on and who might be unresponding.

The most important debugger command at this point is the "v" command, which cycles you through the server screens so you can examine them for clues.

The next most important is the "?" command, which tells you what code you are breaking into. That may or may not be the guilty code.

For more information on CPU Hogs and on using the debugger, follow the link in the Abend Hunting section below for the relevant Wiki page.

If you can't get into the debugger, it is usually a sign of a hardware problem. You should then look to see that all your memory and adapter cards are seated properly, fans are blowing in the right direction, and to consider replacing the memory.

Abend Hunting

High Utilization sometimes turns into an Abend. See the following article for more on diagnosing an Abend AbendHunting.

Room for Corrections

Looking forward to the sysops' notes on this page.