Okey, I have to admit it: I have a lot of CPU power just laying around unused. To be exact, I have around 24GHz available after my two critical hosts have gotten their share.

So, I’m testing the resource pools available for distributing resource shares to different virtual machines. The setup is pretty easy: I have a few critical hosts, namely this web server and the Windows 2003 which is running both my Windows applications and the VMware Infrastructure Server. They are both located on pentagon, a dual 3GHz machine with 7Gigs of RAM.

One of the applications that are using a lot of CPU time is SETI – Search for Extraterrestrial Intelligence – which scans the radio waves picked up with the Arecibo radio telescope. It is notorious for spending close to 100% CPU time.

To test the resource pools and VMware’s ability to distribute resources, I made two pools; the critical and the non-critical pool. The critical is getting a high amount (80%) of the CPU resources while the non-critical is getting a low amount (20%). I then created a virtual machine (linux) to host the SETI setup. This setup was then duplicated to the three hosts that I have running.

I am happy to say that the latency on the critical hosts are close to zero even though my SETI virtual machine is spending almost all the available CPU resources. The host stays at close to maximum CPU utilization at all times, wasting almost no resources.

Well, no happy story without a word of caution: Don’t add your hosts to a DRS cluster, create some resource pools, power on a number of hosts with 100% CPU utilization and then remove the DRS cluster or move one of the hosts out of it. I tried that once with my critical hosts and it quickly came to a point where everything came to a stop. And, since I’m running my virtualcenter server inside a virtual machine, it took some time before I could fix the problem again…. One lesson learned, at least :-)

The picture attached shows my current setup. The current CPU usage is 96,7%. The explanation for the low numbers on the individual CPU’s is HyperThreading which makes the resource monitor a little bit confused. No biggie, the CPU usage monitor for the host displays the right number.