Daniel P. Berrange:
> http://libvirt.org/formatstorage.html#StorageVolBacking
>
> This is currently support for Cow, QCow, QCow2, VMDK and LVM storage
> types. Some of these allow for the underling backing store to be
> writable, others require that its readonly.
I tried the following under libvirt 0.6.0:
vol = pool.createXML("""<volume type="block">
<name>hurgle</name> <capacity>2147483648</capacity>
<backingStore> <path>/dev/VMs/test-disk</path>
<format>raw</format> </backingStore> </volume>""", 0)
It promptly created a volume, but not as a copy-on-write snapshot:
"dmsetup ls --target snapshot" shows nothing, and the image has none of
the data from the test-disk volume.
The pool I used to create these volumes is clearly LVM:
virsh # pool-dumpxml VMs
<pool type='logical'>
<name>VMs</name>
<uuid>bde8f8ed-7e65-8323-ea93-51223d86fedd</uuid>
<capacity>66433581056</capacity>
<allocation>2281701376</allocation>
<available>64151879680</available>
<source>
<name>VMs</name>
<format type='lvm2'/>
</source>
<target>
<path>/dev/VMs</path>
<permissions>
<mode>0700</mode>
<owner>0</owner>
<group>0</group>
</permissions>
</target>
</pool>
You mentioned some constraints about permissions earlier, but I would
have expected that to raise an exception--vol is a valid volume object
and I can query it and mkfs it and so forth. The test-disk volume is
completely quiescent and unmounted. Do I need to prepare it in some
other way to make it suitable for livirt to use as the base of a
snapshot?
(Just for sanity's sake, I verified that libvirt.getVersion() returns
6000)
--
"Forget the damned motor car Nick Moffitt
and build cities for lovers and friends." n...@zork.net
-- Lewis Mumford
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