[Bug 517067] Re: Using virtio for block devices makes disks and partitions disappear in KVM/QEMU (using vmbuilder and libvirt)

[Andreas Ntaflos]

You are right of course, /etc/fstab on the guest contains "/dev/sdXY"
entries. These get generated by
/usr/share/pyshared/VMBuilder/plugins/ubuntu/feisty.py as you mentioned.
After changing all "/dev/sdXY" to "/dev/vdXY" I can indeed boot happily
:)

What threw me off was that QEMU did not (and does not) see these virtio-
based drives when booting (see screenshots) and that changing the target
device name in the domain definition (<target dev='vda' bus='virtio'/>
to <target dev='sda' bus='virtio'/> and vice versa) does nothing. I
suppose this has to do with the snippet of documentation I quoted
previously and probably with the fact that the virtio driver is
paravirtualized so QEMU doesn't do any of the emulation it would do with
IDE- or SCSI-based buses. Should have thought of that earlier.

So creating guests in the manner I described in my original post using
vmbuilder works after applying your one-line fix to
/usr/share/pyshared/VMBuilder/plugins/ubuntu/feisty.py.

I am not sure where this bug lies since I am just getting to know the
more advanced aspects of libvirt but I suppose vmbuider is to "blame".
That's understandable given that it is still somewhat young and cannot
consider all possible combinations and varieties of libvirt options. Too
bad virt-install is mostly useless for quickly creating and deploying
guests for testing purposes.

I like your solution b.) but doesn't that add yet another level of
indirection and complicates guest setup even more?

-- 
Using virtio for block devices makes disks and partitions disappear in KVM/QEMU (using vmbuilder and libvirt)
https://bugs.launchpad.net/bugs/517067
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