[sheepdog-users] Problem with snapshots made with qemu-img

Ing. Luca Lazzeroni - Trend Servizi Srl luca at gvnet.it
Sat Jun 29 16:25:00 CEST 2013

Il 28/06/2013 12:02, Liu Yuan ha scritto:
> On Fri, Jun 28, 2013 at 10:07:47AM +0200, Ing. Luca Lazzeroni - Trend Servizi Srl wrote:
>> Hi,
>> if I make a snapshot of a running VM using:
>> qemu-img snapshot -c Pippo Pluto.raw
>> snapshot is created on all nodes, but its tag is updated on all nodes except the one running the VM.
>> On other nodes I can see, via "collie vdi list" the snapshot tag updated correctly, but on the node running the VM I see 2 VDI with the same name, different ID and empty Tag.
> Seems that recent qemu-img need fixes, we didn't test snapshot with qemu-img
> with our functonal tests. We should though.

Ok. I've also found that using a vdi disk in qcow2 mode with virtio 
produces i/o errors on guests. Using raw images, however, works correctly.
>> If I create the snapshot via "collie vdi snapshot", everything works fine and tag is propagated to all nodes; but I don't know if creating a snapshot with collie of a running VM with writeback cache enabled is a good idea in terms of data integrity…
> No problem, snapshot operation will
> 1 flush the cache first
> 2 mark the vdi as readonly
> If there is, it is a bug that should be fixed.

ok, thanks.

> Thanks,
> Yuan

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