On 05/14/2013 12:34 PM, Leen Besselink wrote:
On Tue, May 14, 2013 at 12:16:32PM +0200, Wido den Hollander wrote:
Hi,
Hi Leen,
Hi Wido,
While working on the CloudStack code for 4.2 I'm running into some
problems with QCOW2 and RBD format 2.
A quick cap of the problem:
CloudStack stores all the templates on "Secondary Storage" as QCOW2 files.
When a VM is deployed, this image will be copied (once) from
Secondary Storage to Primary Storage, this is done by qemu-img which
does the conversion.
When the image is on Primary Storage it will be copied to the
destination volume and the Instance/VM is started.
In that last step I want to use layering, but the problem is that my
image is RBD format 1 due to the qemu-img copy.
I can skip the qemu-img copy, but I have to find a way to go from
QCOW2 to RBD format 2 in preferably one step. There is a issue about
this in the tracker [0], but that won't be finished on time.
Another idea would be to do QCOW2 -> RAW -> RBD format 2, but that
extra step will take a lot of time. It would also require some
temporary storage on the hypervisor.
I also thought of creating the RBD image prior to converting to it,
but that fails, since qemu-img won't let you convert to a already
existing image.
Any brights ideas? Maybe even doing the QCOW2 -> RAW format in
memory? In Java?
I'm no expert, but would it be possible to change qemu-img to support writing RAW to standard out ?
No, qemu-img can't write to stdout. Due to various formats it supports.
So you can run qemu-img convert and pipe that drectly to the rbd import command ?
If qemu-img would support writing to stdout there is the problem that
I'm not using the rbd tool, but Java bindings for librbd and librados.
I'm trying to avoid executing from Java.
rbd import already supports standard in I believe.
Then you don't need any temporary storage.
Maybe something more efficient than RAW is possible as well ?
The goal is to go from QCOW2 to RBD format 2 in one step.
[0]: http://tracker.ceph.com/issues/4897
--
Wido den Hollander
42on B.V.
Phone: +31 (0)20 700 9902
Skype: contact42on
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Wido den Hollander
42on B.V.
Phone: +31 (0)20 700 9902
Skype: contact42on
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