Problem with a RAW Disk and Xen

Jim Fehlig jfehlig at suse.com
Thu Aug 27 19:50:01 UTC 2020


On 8/27/20 3:49 AM, Christoph wrote:
> Hi All,
> 
> I have in config of 2 Xen DomU's this disk:
> 
> <disk type='file' device='disk'>
>        <driver name='qemu' type='raw'/>
>        <source file='/dev/mapper/keys'/>
>        <target dev='xvdz' bus='xen'/>
>        <readonly/>
> </disk>

Using blkback works for me, e.g. <driver name='phy'...>.

> If I start the DomU's then all starts without problem, see this in log
> of the DomU:
> 
> {
>              "pdev_path": "/dev/mapper/keys",
>              "vdev": "xvdz",
>              "backend": "qdisk",
>              "format": "raw",
>              "removable": 1,
>              "discard_enable": "False",
>              "colo_enable": "False",
>              "colo_restore_enable": "False"
> }
> 
> but this disk isn't there in the domU... Why?

It appears readonly disks only work with blkback.

> It is a shared disk between the DomU's but configured as "readonly" so
> there shouldnt be a problem (with the same xen xl configuration, there
> is no problem)

What xl config did you use? It doesn't work for me if I specify qdisk and 
readonly. E.g. the following does not work

"backendtype=qdisk,format=raw,vdev=xvdz,access=ro,target=..."

Regards,
Jim





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