CPU Ready Revisted – Quick Reference Charts

I've written in the past about how high CPU Ready values can cause performance problems in VMware vSphere environments.  For those who don't know, CPU Ready is a measure of the amount of time that a guest VM is ready to run, but the VMware ESXi CPU Scheduler on the host is not able to immediately allocate cycles to the guest because it is busy doing work for other VM's.  CPU Ready values are exposed through ESXTOP and in the vSphere Client. I'm often called into customer environments to do performance troubleshooting, and CPU Ready is one of the first performance measurements I check my … [Read more...]

The Skinny on ESXTOP

A reader named Mark contacted me today and asked if there was a way to reduce the size of the batch output from an ESXTOP run.  And he asks for good reason: Depending on the number of VM's on your host, the delay between ESXTOP samplings and the number of samples you collect, using the All Stats option (-a) can yield a massive file in a short period of time.  If written to a partition on your ESX Service Console you run the risk of filling the partition, and forget about actually being able to analyze the data in PERFMON or Excel.  For example, on an ESX host running ~15 VM's I produced 100MB … [Read more...]