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Best Practice Advice - Server 2K8 R1 High CPU Utilization on ESX 3.5 U4

David Blair
David Blair asked
PROBLEM: High CPU utilization on VM guest OS.

My ESX 3.5 U4 hosts four production servers.  Three are 2003 R2 and one is 2008 R1.  The 2003 VMs run just great (and I mean GREAT), but the 2008 installation is really slow, in fact the task manager performance tab hangs out at around 40-50% with just core services (wmiprvse.exe, System, etc.).  It peaks to 100% frequently with even the slightest activity.  The 2008 VM has one virtual processor.  Everything here is 32 bit.  

The 2008 VM functions as a DFS file server and backup domain controller only.  This was the only VM that was not P2V'd.

Hardware environment is a ML570 G2 quad Xeon 2.8 with 12GB RAM.  Yea it's old, but it works great and should be plenty fast enough for the workload.

I can see in vCenter that the guest performance peaks at about 2,800MHz of CPU.  There is plenty of host processor resources available when I look at the ‘Performance’ tab of the host.  Also, there is sufficient RAM available.

Is something configured incorrectly?  Is the amount of CPU available to the guest somehow limited by the clock speed of the host CPUs?  I know that sounds like a n00b question, but I’m really confused here.  Should really just migrate the 2008 VM to a faster host?  Should I utilize virtual SMP?
Watch Question

Top Expert 2015
You should use at least two virtual cpus to get MP kernel on any release of Windows. Adding 2nd CPU on uniprocessor system does no change.
There is U5a supporting all releases of 2008 and making you eligible for asking vmware support.


Yesterday I increased the number of virtual processors from one to two.  I can see a noticable performance improvement, and the performance tab in vCenter now goes above 2,800MHz, which is definately a good thing.

It still seems to lag a bit on tasks that should be a breeze.

You mentioned ESX 3.5 U5 in your reply - are there specific performance advantages for our environment?

Please update the type of Storage you are using. (DAS, NFS or SAN)
On the ESX 3.5 U5 Upgrade part, upgrading helps you to fix certain bugs and patch certain vulnerabilities. In addition to this, you get the option to install additional Guest Operating Systems.
If you have a valid SnS with VMware, I would suggest that you upgrade to ESX 4.0 U1.
Top Expert 2015

U5 contains security patches and is compatible with all releases of 2008
I cannot help with your "environment", extreme random delays in network functions of Windows are common independently of vmware