Your Virtual Machine seems slow? Stop, think, read, re-think.

We’ve all been there. VM appears to run slow, users complaining about a service that’s been virtualized, etc. First thought, oh must be a VMware problem, let’s call them. Wrong. Stop and think for a minute. Most such issues are due to a poor configuration, poor set of setup choices or simply not understanding what is going on!

Do some due diligence. Simple troubleshooting gets you pretty far into understanding what is going on from the Guest OS perspective, but more importantly from the ESX host perspective as well. Get familiar with esxtop, the VMware tool equivalent of top with lots of steroids.

Some of the first things you should do is take a look at esxtop (ssh/iLo to the ESX host the VM is on and run esxtop as root). The first screen you get is looking at CPU usage. Locate your VM and take a look at the %RDY time (DOC-7390).

Lots more on performance here:

and the performance community:

esxtop and VC performance tools:

In the end you’ll learn something, and you’ll have enough information to get your problem resolved more quickly on your own. If not, you’ll have to wait for VMware Support (who are made of awesome) to get around to looking at your configuration, and proving you’ve got things configured wrong. Do you really want to wait a while just to find out you did something wrong? Waste of time isn’t it? How embarassing.