Virtual machine performance on software RAID 0 (stripe) in Windows

Posted on 2007-10-07
Last Modified: 2008-01-09
I would like to know what people's experiences have been with running VM's off software raid 0 volumes in Windows XP or Windows 2003.

Specifically I am running a classroom of PC's and we use VM's every day. We need to upgrade them. I am looking at options. One option is to upgrade disk, another is to replace the whole box.

Current spec:
Pentium 4 2.8GHz, Prescott

Proposed upgrade:
Add 160GB HDD, split into two partitions, one for OS, then make a stripe over 160GB and 80GB drives.
Run virtual machines off stripe.

I don't really care what free VM software we use, but we are running on top of Windows 2003.
e.g VMWare Player, VMWare Server, Virtual PC 2007, Virtual Server are all options.

OS we run in VM include: Knoppix, Ubuntu, XP, 98, 2003, Vista, Server 2008.

So my question is:

What kind of performance increase am I likely to see running VM's off a software stripe volume in Windows 2003?

Example answer: Your VM's will boot about 30% faster. Overall responsiveness will improve. Running several VM's concurrently will be noticibly faster and smoother. Vista on stripe will run about as fast as XP on no stripe.

Question by:harrowc
    LVL 4

    Expert Comment

    by:Bart van der Wee
    Running on Windows 2003 x64, I achieve 40MB/s on my single SATA drive.
    On my RAID 0 SATA stripe (2 disks) I achieve 88MB/s. This is the volume I run my Virtual machines from and I would say as long as the .vmdk files are not fragmented you would not notice any difference in the virtual machine compared to the physical machine.
    I run a Dual core 3GHz processor and 2GB RAM. One word comes to mind: smooth -> the virtual machines on the stripe run smoothly even with four or five running at a time, (this includes XP Pro, Linux, and Windows 2003 images).
    Hope that helps,
    LVL 3

    Author Comment

    Bart, thanks for your contribution.
    Unfortunately your PC is so different to ours I cannot make a comparison.
    For example:
    - your CPU supports 64 bit and Virtual extensions
    - your CPU is dual core
    - you seem to be running hardware RAID, not software RAID. I cannot use HW because the motherboard does not support it (old).

    Also you did not make it clear whether your performance changed when running off a stripe, only that is smooth.

    LVL 4

    Accepted Solution

    I am running a windows software RAID 0, from what you have posted I suggest you look at one drive for the Host OS and then two additional drives for the RAID 0 and virtual machines. You will get a definite performance improvement when you run your virtual machines on a different physical drive to your operating system.

    What you propose with only two disks will be limited in overall performance due to the fact that the Host OS is still using one of the drives.
    LVL 3

    Author Comment


    To further complicate matters, there are only 2 sata ports and the cases are very small, and with the P4 prescotts being very hot, I would not consider putting more than one extra hard drive in.

    Did you notice what kinds of workloads went faster under raid 0?

    LVL 4

    Expert Comment

    by:Bart van der Wee
    What I noticed the most was when using XP as a VM it was difficult to tell it was a VM and similarly my main OS did not slow down at all even when running multiple VM's running various applications.
    LVL 1

    Expert Comment

    Forced accept.

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