Experience Running MS SQL 2008 on a Win 2008 in a KVM Virtual Machine

kvm-virtualizationwindows-server-2008

I am thinking of either running MSSQL 2008 on a bare metal machine or in a Ubuntu Guest based KVM virtual machine. The server itself is quite well provisioned.

I want to use KVM, but my primary concern is the disk I/O – directly vs through the KVM based VM.

Does anyone know:

  1. If the I/O performance is
    comparable?
  2. Are there any drivers
    that make win 2008 perform better on
    a KVM or are these already part of
    the KVM base virtualization?
  3. Any tools/scripts/command I can run to
    compare my bare metal I/O thoughput
    to that via the VM.

Any other advise would be welcome…relatively new to this 🙂

Thanks!

Best Answer

  1. Performance is not 100% the speed of the disk subsystem, but pretty close if you avoid overhead. In general, it is recommended to use raw, preallocated images, and use qcow2 only for snapshots.
  2. Virtio drivers can make the VM go much faster. They are available from linux-kvm.org.
  3. iozone comes to mind

I have seen ubuntu and gentoo act weird with kvm, which has been fixed by a reinstall of the right packages. Never seen the same on fedora or RHEL though - everything works out of the box there.

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