The Hitchhikers Guide To ESXTOP Counters

For all the other performance people out there that spends time using esxtop to do deep analysis of ESX performance, there is a great document that you really should know about.  It is called vSphere Monitoring and Performance for vSphere 5.1 / vCenter 5.1 / ESX 5.1.

My favorite section is a detailed list of all the esxtop counters and exactly what they mean and how they inter-relate.

For example, I had a question about what is the difference between the %USED and %RUN for a VM.  On page 155 and 156 of this great document it gives you the specific formula for %USED, which is:

%USED = %RUN + %SYS - %OVLP

It also explains in the %RUN definition that on systems with hyperthreading enabled, the %RUN value does not account for hyperthreading.  This can cause %RUN to be twice as large as %USED.  But wait this can't be possible based on the formula - except in this case it is because %USED accounts for hyperthreading.

Another mystery of the universe is solved with the help of the vSphere Monitoring and Performance guide.