Guest CPU 100% fixed by decrease in RAM...why?

[naterunge]

This one has me stumpted...

Windows 2008 R2 Standard VM

ESXi 4.1 Update 1

Enterprise Licensing

Cisco UCS Blade w/ Dual 6 Core Procs and 198 gigs of RAM

Host RAM utilization below 30%

vmxnet3 and pvscsi drivers

latest VmTools

300gig Datastore is FC Disk over 4GB fiber (85% of datastore in use by the single VM, all disks thin provisioned)

When I migrated the Windows 2008 VM over to the new blade I bumped it up from 4 to 16 gigs of memory. After that even the most minor file copies to a CIF share would consume 100% of the CPU. After taking the RAM back to 4 gigs the issues went away.

We have many other VM's on our UCS running with similair specs and no problems with CPU performance. The one big difference is that the datastores that those VM's live in are not as full.

The other difference is that this VM was migrated from an old cluster using EVC. Disabling EVC on the cluster and completely shutting down the VM and restarting twice for the hardware changes had no effect. Thouht I would mention it anyway.

Just trying to put the peices together so that I can avoid causing similair issues in the future.

[idle-jam]

could it be due to that the memory swapping/paging has occurred and the processor is busy doing such activity

[Dave_Mishchenko]

Did you have a chance to see what process was consuming the CPU in the VM?

[AndreTheGiant]

Welcome to the community.

As written check in the guest OS which process use so much CPU.

About EVC is very strange that without it the VM does not run at all. This happens on all hosts? Maybe you have manual CPU Mask at VM level?

Andre

[bulletprooffool]

Hi - welcome to the community . .

According to http://msdn.microsoft.com/en-us/library/aa366778%28v=vs.85%29.aspx#physical_memory_limits_windows_se... Windows 2008 standard has a 4GB memory limit on x86 processors.

What version of Win2k8 are you using?

[Walfordr]

Alan Gerald wrote:

Hi - welcome to the community . .

What version of Win2k8 are you using?

He's running 2008 R2 which is 64bit only OS.

naterunge wrote:

This one has me stumpted...

Windows 2008 R2 Standard VM

ESXi 4.1 Update 1

Enterprise Licensing

Cisco UCS Blade w/ Dual 6 Core Procs and 198 gigs of RAM

Host RAM utilization below 30%

vmxnet3 and pvscsi drivers

latest VmTools

300gig Datastore is FC Disk over 4GB fiber (85% of datastore in use by the single VM, all disks thin provisioned)

Like the others suggested, check which processes in the VM guest OS is using up the cpu.  This will help you better trouble the problem.

Note that when you upgraded the VM ram to 16GB you added 12GB more to the swap file (that is created on VM boot up) on the LUN.  I do you know if the mentioned 85% was before the VM memory upgrade.