Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I've been trying out VMware server for a while using different guest OS. On all of them I've seen the same thing - a lot of CPU is used when accessing the host's disks from the guest. The System process is using the most. I've tried with both Windows 2003 and 2008 as host OS with the same result. I'm using the standard bridged network setup.

I would be grateful for anything I could try to get the CPU load down as this problem makes the setup quite unuseful.

share|improve this question
Which VMware product? Workstation or Server? And what do you mean by accessing the hosts disks from the guest, are you mapping directly in via the Hypervisor or are you using standard networking? – Helvick Feb 9 '10 at 0:38
Sorry. It is server. – girishvmware Feb 9 '10 at 0:43

Unfortunately in my experience this is pretty normal -- VMWare guest disk performance is crap unless you spend some cash on the host's disk hardware (fast 15K SCSI drives + big controller caches, SANs, etc.).

The one recommendation I have is to use preallocated disks. If you use growable disks your clients stall while VMWare needs to allocate more (real/physical) disk space, and the virtual disks themselves can become fragmented which wrecks the OS disk optimization your guest systems may be trying to do & can cause the guest OS to spend a lot of "system" CPU cycles waiting for reads/writes to return.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.