Bad performance with VHD disk

[jschwart]

I'm using VirtualBox with an virtual machine image that I didn't bother to convert so it is still a VHD image. Right now its size is 36GB. I notice that my VM is spending a *lot* of time on accessing its virtual disk.

Could there be a performance issue with VHD images? Could this be solved in VirtualBox or should i really convert my image? Is there any info I could provide to help solving this?

[mpack]

If the performance hit is significant then I doubt it has anything at all to do with the container format. More likely is that you neglected to remove VirtualPC tools from the VM before copying it to VirtualBox.

[jschwart]

Yes, it's quite possible it is something else, but what I see is that when the VM is slow, there is always a lot of disk activity. I did remove the Virtual PC tools, they are not there anymore. Btw. the guest is Windows 7 32-bit.

[mpack]

To answer your original question, VirtualBox has no known issues concerning VHD performance. If the guest is thrashing the disk for some reason then perhaps you should look to more conventional causes, such as lack of memory, excessive network activity etc, excessive virus scanning etc.

[jschwart]

Thanks a lot for your reply!

It seems there are indeed other factors involved. One thing I noticed is that my guest runs significantly slower when I start it from Windows 7 than when I run it from Ubuntu 12.04.

[mpack]

That again sounds like lack of memory, perhaps your Ubuntu host is left with more working memory once the VM has been assigned its portion.