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...]

Balloon Driver Problems with SQL

I have been meaning to write this up for a while; Scott Drummonds' 'Love Your Balloon Driver' post today at his Virtual Performance blog gave me a nice reminder.  I actually caught a sneak peak at the graphs with an explanation from Scott at his instructor-led lab at VMworld 2009.  Scott calls out that the only workload they discovered suffers from balloon driver activity is Java.  The reason for Java's problems with balloon driver activity is that Java itself runs in a VM and so the guest OS cannot properly determine which pages should be swapped out when the balloon driver calls for … [Read more...]