After running well for two months, my VM has suddenly slowed to a crawl. I
cannot identify the problem - can anyone suggest what to try or how to
diagnose it?

I apologize if this is a double post. My first post did not seem to go
through.

Details:

Platform = Intel dual core CPU and board supporting VT, 8 GB RAM, VPC 2007.
Host = Vista x64.
Guest = Win XP Pro x86, 2 GB RAM, with hardware virtualization enabled.
VHD = dynamically sized, max 64 GB, current 39 GB, on an independent
physical drive with 89 GB free space.

The Task Manager of the host typically reports 3-10% CPU usage.

The Task Manager of the guest reports 20-100% CPU usage. On the Processes
tab, the only usage is System Idle Process (80%), explorer.exe (10%), and the
Task Manager itself (10%).

I perform many installations and uninstallations on the VM, mostly new
builds of my customer's software. Except for that, I did not install software
or reconfigure the VM recently.



The problem is intermittent. The guest performance is occasionally good, but
usually slow. The host performs fine.

Defragmenting the guest did not help. I did not try defragging the host
because Vista runs a scheduled defrag every week.

--
David Shaked

You might try and uninstall the VPC additions an reinstalling them,
sometimes an update can override some of the performance enhancements.

--
Bob Comer



On Tue, 14 Jul 2009 14:02:01 -0700, David Shaked
<DavidShaked@xxxxxx> wrote:

>After running well for two months, my VM has suddenly slowed to a crawl. I
>cannot identify the problem - can anyone suggest what to try or how to
>diagnose it?
>
>I apologize if this is a double post. My first post did not seem to go
>through.
>
>Details:
>
>Platform = Intel dual core CPU and board supporting VT, 8 GB RAM, VPC 2007.
>Host = Vista x64.
>Guest = Win XP Pro x86, 2 GB RAM, with hardware virtualization enabled.
>VHD = dynamically sized, max 64 GB, current 39 GB, on an independent
>physical drive with 89 GB free space.
>
>The Task Manager of the host typically reports 3-10% CPU usage.
>
>The Task Manager of the guest reports 20-100% CPU usage. On the Processes
>tab, the only usage is System Idle Process (80%), explorer.exe (10%), and the
>Task Manager itself (10%).
>
>I perform many installations and uninstallations on the VM, mostly new
>builds of my customer's software. Except for that, I did not install software
>or reconfigure the VM recently.
>
>The problem is intermittent. The guest performance is occasionally good, but
>usually slow. The host performs fine.
>
>Defragmenting the guest did not help. I did not try defragging the host
>because Vista runs a scheduled defrag every week.

The problem is now solved.

The biggest improvement occurred when I detached the VHD and switched to
another VHD disk, and then returned to the original VHD. I can only speculate
that something was corrupted in the VMC file, and switching the disks fixed
it.

I then applied Robert Cormer's advice and other advice that I found on the
web:

- I discovered that I had installed VPC 2007, rather than VPC 2007 SP1. I
installed SP1.
- I uninstalled and re-installed Virtual Machine Additions.
- I defragged the guest and host again.
- I ran the precompactor and compactor. The VHD size shrank from 40 GB to 19
GB.

The guest performance has now been fully restored. When no applications are
running, the guest Task Manager reports 0-3% CPU usage.

For the future, I guess I must plan regular VHD maintenance operations such
as defragging and compacting.

--
David Shaked