windows 7 install 3x slower using kvm
 

I have a machine with a 3ware hardware raid card in raid 5, core 2 quad, and 8GB ram. Installing Windows 7 directly on the hardware took 15:34 (mm:ss) and doing it with qemu/kvm and a qcow2 type image took 42:10. That seemed like a pretty significant slow down to me. Is this level of degradation expected or have I done something wrong? The command I used to run the kvm install was:

During installation you are using the default QEMU emulators without the benefit of any tuning so expect it to be slower.

After installation you can start tuning your guest. Depending on the type of usage you may choose to migrate to the raw format instead of the qcow2 format for a slight speed increase. Changing to the virtio ethernet and block paravirtual drivers along with the installing the Windows guest drivers will also help with speed increases.

Don't expect the final product to be as fast as a bare metal Windows install but it should get better than the initial install speed.

You should check, that you have actually enabled kvm. You can do this by running the command 'info kvm' inside the qemu monitor. If kvm support is not enabled, you may not have loaded the required kernel modules (modprobe kvm; modprobe kvm-(intel/amd)

Personally I have seen a speed boost with the combo kvm-kmod-2.6.32 and the recently "released" qemu-kvm-0.12.0-rc2. Note, those packages are not intended for production servers, but give them a try.

I reconfigured qemu-kvm to use an LVM partition directly for the c drive and my install dropped to 17 minutes, almost as good as native.

However, I installed using VirtualBox and an LVM partition and my install time dropped to about 10 minutes. That's better than native!