Am 04.03.2013 um 14:09 hat Daniel P. Berrange geschrieben:
> On Mon, Mar 04, 2013 at 01:58:12PM +0100, Ján Tomko wrote:
> > Before posting another version of my patches [1], attempting to add
> > support for the new qcow format to libvirt, I would like to know if this
> > sounds reasonable:
> >
> > A new format named 'qcow3' would be added, along with a <features>
> > sub-element for target.
> >
> > <volume>
> > <name>qcow3test</name>
> > <source>
> > </source>
> > <capacity unit='GiB'>8</capacity>
> > <target>
> > <path>/var/lib/libvirt/images/qcow3test</path>
> > <format type='qcow3'/>
> > <features>
> > <lazy_refcounts/>
> > </features>
> > </target>
> > </volume>
> >
> > I think that libvirt shouldn't care if the features are compatible or
> > incompatible, as we don't know what features are supported by the
> > hypervisor. Would the features be any good as tri-state (on, off, default?).
> >
> > While the qcow3 format is handled by the qcow2 driver in QEMU,
> > <driver name='qemu' type='qcow2'/> should be enough for domains,
>
> We should use qcow3 everywhere IMHO, regardless of whether qcow2
> technically works in this context.
I think it makes much more sense to deal with it the way qemu does
instead of inventing new names. This has much more of an (incompatible)
feature flag than of a different image format. So to fit it in your
proposed syntax:
<target>
<path>/var/lib/libvirt/images/qcow3test</path>
<format type='qcow2'/>
<features>
<compat version="1.1" />
<lazy_refcounts/>
</features>
</target>
Or if you really think that you should refer to the inner workings of
qcow2, you can make it <version>3</version>.
But I guess you call all VMDKs just "vmdk", despite the fact that they
are really just a collection of different subformats. Right?
Kevin
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