Effect of mixed CPUs on PA-RISC N4000

[Matthew Couper]

I have recently taken over the system duties at a new company, and realized I have never encountered this situation before, but can't determine if it is actually something to worry about.

We are running HPUX 11.0, 8xPA-RISC, however the system has 7 PA-RISC 8500 and one PA-RISC 8600.

The only thing is, I don't see any bottleneck apparent in glance, the processor seems to be computing as normal; and no system errors are shown in the logs.

Is the processor downward compatible, or could there some hidden issue that could be causing Bus speed issues/errors.

I would expect a problem, but none is visible. How can I determine if there are problems - I have tried sar -q and -u and don't see any apparent problems.

Also, is this something that I should resolve immediately, or is a mute issue. I was always under the assumption SMP systems MUST use the same processor levels, and preferrably processors from the same product bin or atleast country of production atleast.

Matt

[Devender Khatana · Accepted solution]

Hi Mathew,

For some systems the mixing of processor speeds is allowed and works without problems. But the disadvantage here would be that all the processor will work on the frequency of the slowest CPU.

Also the bus also will work at the frequency supported by the slowest CPUs. So you are not utilizing other processors and buses to full extent. The reason here for system not showing problems here related to here would be perhaps that the utilization is not loaded.

But in my opinion the server should have shown some performance problems if it would have been a more loaded server.

Here is the link describing mix of processors in a N-Class.

http://www2.itrc.hp.com/service/iv/docDisplay.do?docId=prodITRC/WW_HW_UX_NC_EN_E/n_config.htm#CPU%20Configuration

HTH,
Devender

[Devender Khatana]

Hi Again,

Here is another link describing replacing one processor with a different one.See page 20


http://www2.itrc.hp.com/service/iv/docDisplay.do?docId=prodITRC/WW_HW_UX_NC_EN_E/n4000whitepaper.pdf

HTH,
Devender