Wednesday, August 24, 2016

Windows Guest: VMware Perfmon metrics intermittently missing?

I'm using logman to collect Windows, SQL Server, and VMware metrics in a csv file(30 second intervals).

Not sure what's causing the sawtooth pattern below.  I thought it was a timekeeping problem on the ESXi host, now not so sure.

See this Ryan Ries blog post for what may be a similar issue, caused by clock sync of guest with ESXi host.!
But that is also a reversal of the problem somewhat.  In that case, guest metrics were returning -1.  In my case, its the VMware metrics (passed through from the host) that are missing.

The same pattern for "Host processor speed in MHz" adds to the mystery.
If only "Effective VM Speed in MHz" was missing, I'd chalk it up to a possible arithmetic issue, with a negative denominator resulting from time skew between guest and host.
But... "Host processor speed in MHz" should be a constant 2600 in this case.  Maybe somehow its still calculated with a time interval, and time skew can screw it up?

For now, I've got a loop running on this VM logging local time, and using NET TIME to retrieve time from another VM as well.  That's turned up variations, but it seems to be variations of up to 5 seconds in contacting the other VM rather than large time skew between the VMs.

Guess I'll see what turns up...

So far this is the closest I've found.  Similar problem reported - no resolution.

"Windows VM perfmon counters - VM Processor"

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