High avg cpu usage on ESX but not in guest OS?

[allanredo]

Hi, i have a question why the ESX 3.5 host reports a average cpu usage for a certain guest of about 2000mhz out of 4500, when pertmeter in guest os display hardly any cpu usage at all, 1-3% ?

The guest is a w2k AD server running sql 2000 and exchange 2k and is functional like a charm, im just wondering about this behavior?

Server is a dell 2950 + esx 3.5.

The avg memory in usage reported by ESX is about 3 gb but guest os claims it is using all 4gb granted to this guest?

I guess all this is normal behavior by the smart esx and not magic, but im curios anyway.

Any hints on documents where i can read up on this interesting phenomena...

The guest is imported using vmvare converter, other guests on the same esx shows idle host cpu usage when gues is also idle. both imported and installed guests.

tia

[RParker]

Well depending on the number of VM's an ESX has to host, the CPU increases with each VM managed.

So the numbers you are seeing (and guessing from the difference in the VM CPU vs host CPU, I'd say you have around 18 VM's) are relevant to the ESX overhead of managing each of the VM's. Each VM, even idle, need about 200-300 mhz of HOST CPU to stay running.

So all in all this is normal. Which is why they don't recommend running to many VM's (more than the 4:1 consolidation ratio) due the fact that the CPU will be very high with too many VM's, and it becomes counter productive.

[allanredo]

Hello, thanks for your reply. I can understand that esx requiers cpu to manage several guests.

However in my case it is not the esx that show 2000mhz of usage, it is one guest only. the same that displays idle cpu at the same time.

Everything else is more or less idle in the host.

tia

/a

[JRink]

Was this P2V'd? There seems to be a bit of a problem with P2V'ing Windows 2000 boxes as it relates to this problem. If you search the forums, you'll find quite a number of posts about this. You can search posts in my username as well as I've posted some in the past...

[Anders_Gregerse]

There can be several sources for this kind of symptom. Usually it's because a single cpu vm is configures with a multiprocessor HAL (see device manager, show hidden devices), it can also be because it is using cpu instructions that cause a load on the physical cpu, but with the software you mention, my guess would be the first option.