[virt-tools-list] issues with graphics driver and qcow2

Nick Gilmour nickeforos at gmail.com
Sat Aug 19 14:48:00 UTC 2017


Hi Pavel,

thanks for the quick response!

1. Installed versions:

   - Host: KDE neon 5.10 (based on Ubuntu 16.04.1)
   - Guest: Linux Mint 18.2 Cinnamon
   - virt-manager: 1:1.4.2-1~getdeb1
   - libvirt: 1.3.1-1ubuntu10.12
   - qemu: 1:2.5+dfsg-5ubuntu10.14
   - kernel: 4.10.0-32-generic

2. I have set a sorage size of 100 GB with qcow2 and my host reports 100
GB. I have also created some test disks with other formats to check how
they behave:

   -  qcow2: max: 2 GB - actual size: 2 GB
   -  qcow: allocate 1 GB, max: 2 GB - actual size: 8.5 KB
   -  vdi: allocate 1 GB, max: 2 GB - actual size: 8.5 KB
   -  vmdk: allocate 1 GB, max: 2 GB - actual size: 320 KB
   -  raw: allocate 1 GB, max: 2 GB - actual size: 2 GB

Nick




On Sat, Aug 19, 2017 at 4:07 PM, Pavel Hrdina <phrdina at redhat.com> wrote:

> On Sat, Aug 19, 2017 at 03:32:58PM +0200, Nick Gilmour wrote:
> > Hi all,
> >
> > I have just installed KVM, QEMU and Virtual Machine Manager and created a
> > VM with Linux Mint 18.2 on it. Everything looks good except 2 things:
>
> Hi, can you please share with us what OS are you using and versions of
> virt-manager, libvirt, qemu and kernel packages?
>
> > 1. The graphics driver is apparently not working properly. I have tried
> all
> > of them incl. QXL, VMVGA ( with Virtio I get error: virtio-gpu 3d
> > accelaration is not supported) but I always get this popup message
> "running
> > in software rendering mode". Besides that, I there is no option to rotate
> > the display. How can I fix this?
>
> The preferred video devices are QXL or virtio, you should be able to
> disable 3D acceleration for virtio-gpu.  If you follow this guide [1],
> it should be possible to enable 3D acceleration.
>
> > 2. As far as I have read the difference between qcow2 and qcow storage
> > format is that qcow2 is a successor of qcow. When I choose qcow2 there is
> > no option for max size i.e. it has a fixed size. Is this correct? Is
> qcow2
> > for fixed size and qcow for dynamic size?
>
> The qcow2 is in most cases the best choice.  The reason why there is
> only one size option is because how qcow2 format works.  If you set for
> example 50G, it will not allocate 50G on your disk.  The file itself
> will be only few KB large.  It will grow automatically with the usage.
>
> Pavel
>
> [1] <https://www.kraxel.org/blog/tag/virtio-gpu/>
>
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