Fibre Channel (SAN)

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Occasional Contributor
Posts: 17
Registered: ‎10-09-2014

The meaning of IO_PERF_IMPACT

We've recently turned off bottleneckmon and turned on MAPS FPI monitoring.  We're used to the idea of latency being when the buffers fill up and frames are lost (and so IO_FRAME_LOSS messages make sense), but we're not entirely sure what IO_PERF_IMPACT really means.  We get a lot of alerts for one particular port that read similar to:

 

2016/06/28-07:27:13, [MAPS-1003], 10650, FID 128, WARNING, c80fsw113,   F-Port 43, Current Value:[DEV_LATENCY_IMPACT,IO_PERF_IMPACT, 31.2% of 10 secs], RuleName=LHR_Latency_Perf_Impact.

 

But this doesn't cause ANY issues - there are no errors in porterrshow, portstatsshow, portshow, no impact to the connected server.

 

Is this normal?  Is this something we can just ignore?  What does the 31.2% of 10 seconds actually mean?  Might this be something to do with TX Credit Zero?

 

Any advise appreciated - the manuals and Google don't shed much light.

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