Hello,
I have this same problem with CPU usage. I'm hoping someone knows the real answer to this problem.
One VM on a host has a very irregular CPU usage pattern. It shows consistent spikes of CPU up to 100% every 20min. The vendor said this was expected. They also said to use the default alarms and didn't have a good solution for this either (Interesting coincidence, don't you think).
From what I can gather, I would need to delete the default, vm, CPU alarm on the vCenter level. Then re-create that alarm on the host level for every ESX server except for the one hosting the VM I need a "special" CPU alarm for. Finally I would re-create the base alarm on all the VMs on that host except the "special" one.
At last I can create a good alarm for this one crazy VM's cpu usage.
That seems like a lot of work. And stupid.
The only other viable solution would be to monitor each VM individually with a standard element monitoring solution.
--
Dave