Qemu can work with vmdk but some features of vmdk aren’t used. So I can understand vmdk is slow.
Best practice: 1. Use LVM is you can (harder to transfer/copy images) 2. Alternative raw-file for speed (but you lose functionalities) 3. Qcow for functionality in a file image (snapshots, compression,…) I think other formats are supported for compatibility reasons in testing and migration scenarios, not for production environments. Van: libvirt-users-boun...@redhat.com [mailto:libvirt-users-boun...@redhat.com] Namens John Obaterspok Verzonden: vrijdag 19 februari 2016 7:16 Aan: Martin Kletzander CC: libvirt-users@redhat.com Onderwerp: Re: [libvirt-users] Sluggish performance with virtio and Win10 2016-02-18 15:15 GMT+01:00 Martin Kletzander <mklet...@redhat.com<mailto:mklet...@redhat.com>>: On Thu, Feb 18, 2016 at 12:59:52PM +0100, John Obaterspok wrote: 2016-02-18 11:25 GMT+01:00 Martin Kletzander <mklet...@redhat.com<mailto:mklet...@redhat.com>>: On Thu, Feb 18, 2016 at 10:41:42AM +0100, John Obaterspok wrote: 2016-02-18 10:13 GMT+01:00 Martin Kletzander <mklet...@redhat.com<mailto:mklet...@redhat.com>>: On Thu, Feb 18, 2016 at 08:49:38AM +0100, John Obaterspok wrote: Hello, I'm using virt-manager on my F23 box to run a Windows 10 image but the performance is so bad it's killing me. I have "vmx" flag in /proc/cpuinfo # lsmod |grep kvm kvm_intel 167936 6 kvm 503808 1 kvm_intel virtio-win-0.1.112-1.noarch But no virtio modules loaded. Should they be loaded nowadays? Not on the host AFAIK. The disk format used is vmdk with no caching and native mode. The io is 100% in windows task manager performing less than 1MB/s Any clues? What are the figures from the host? What is qemu doing and what are the other processes and devices doing? What is the best way to find this out? {,a,h}top should do for the initial runs, just to see if the block layer is busy or the CPU is busy or something else is blocking it atop seems to indicate that sdd is busy? DSK | sdd | busy 96% | | read 1455 | write 1319 | KiB/r 5 | KiB/w 9 | | MBr/s 0.74 | MBw/s 1.26 | avq 1.01 | | avio 3.43 ms | # mount | grep sdd /dev/sdd2 on /vm type ext4 (rw,relatime,seclabel,data=ordered) And it doesn't do that in any other process on the host? It looks like it's not related to virtualisation... Hi, I changed from vmdk to raw and the Write performance went from 1.6 MB/s to ~100 MB/s Is vmdk write performance so bad? Result: http://postimg.org/image/gcqe5affn/ -- john
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