[libvirt] libvirt disk labels and QEMU drive host alias generation

Daniel P. Berrange berrange at redhat.com
Tue Jun 14 11:01:52 UTC 2016


On Tue, Jun 14, 2016 at 12:50:09PM +0200, Kashyap Chamarthy wrote:
> Summary
> -------
> 
> It seems like libvirt is generating the same QEMU drive host
> alias ('drive-virtio-disk%d') for different two disk labels (vdb, vdb1).
> 
> [Refer the contextual root cause analysis discussion at the end with
> Laine & Peter.]
> 
> Let's take a quick example to demonstrate the issue.
> 
> On a guest that is shut down, attach a couplee of disks with labels
> 'vdb', and 'vdb1'
> 
>     $ sudo virsh attach-disk cvm1 \
>          /export/vmimages/1.raw vdb --config
> 
>     $ sudo virsh attach-disk cvm1 \
>          /export/vmimages/1.raw vdb1 --config

That second command is user error - hotplugging a disk partition
is nonsensical, except with Xen which allows that for paravirtualized
disks. We should reject such disk names with an error right away in
all other cases.

Regards,
Daniel
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