Host vs VM Guest Performance Counters, which is right?
Posted by Rob Risetto on May 02, 2015
I thought it would useful to highlight to readers that there can be differences in what a VM Guest performance counters show verses similar counters presented by the VMware performance charts. The following articles provide an insight into some of the discrepancies you may face.
The first article Virtualization resource consumption counters lie to you is from David Klee (SQLServerCentral.com) provides insight into VMware active memory counter interpretation when SQL Server buffer pool memory is not being updated but only being accessed for reads. His core point is that VMware administrator could inadvertently interpret that the memory is not being used and therefore decide to trim down the memory allocated to the server.
The second article A tale of two metrics: Windows CPU or vCenter VM CPU is from the monitoring company LogicMonitor and provides a comparison of the CPU capture and charts at the Guest OS level and VMware host level. The article provides a good explanation on why CPU utilisation may vary between Guest and Host CPU charts. It also highlights the CPU Ready counter and associated chart as an essential item to review. See my previous post on the CPU Ready counter, Is Your VM Sluggish, then Check Out the VMware CPU Ready.
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