[libvirt-users] [Qemu-devel] Sluggish performance with virtio and Win10

[Stefan Hajnoczi]

On Fri, Feb 19, 2016 at 08:50:12AM +0100, Martin Kletzander wrote:
> On Fri, Feb 19, 2016 at 07:16:12AM +0100, John Obaterspok wrote:
> >I changed from vmdk to raw and the Write performance went from 1.6 MB/s to
> >~100 MB/s
> 
> Now that's interesting!  Of course raw will be faster but by 2 orders of
> magnitude?  That seems unreasonably much more than it should be.
> 
> >Is vmdk write performance so bad?
> >
> 
> I can't say, I wouldn't even expect that -- that's why I didn't even
> suggest it.

The only native formats in QEMU are raw, qcow2, and qed.  They support
parallel I/O.

All other formats are only suitable for qemu-img convert so you can
import/export images.

Depending on the workload there can be a large performance difference.

Stefan
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