Hi Stefan,
As per documentation, Nova (Openstack Compute layer) is doing a
'qemu-img convert -s' against a running instance.
http://docs.openstack.org/trunk/openstack-compute/admin/content/creating-images-from-running-instances.html
Do you think it could be our root cause ?
Btw, I tested cache=writethrough and I observed image corruption after
some time ('qemu-img check' returns errors)
Thanks for your input,
-Sylvain
Le 13/02/2013 10:03, Stefan Hajnoczi a écrit :
On Tue, Feb 12, 2013 at 03:30:37PM +0100, Sylvain Bauza wrote:
We currently run Openstack Essex hosts with KVM-1.0 (Ubuntu 12.04)
instances with qcow2,virtio,cache=none
For Linux VMs, no trouble at all but we do observe filesystem
corruption and inconsistency (missing DLLs, CHKDSK asked by
EventViewer, failure at reboot) with some of our Windows 2003 SP2
64b images.
At first boot, stress tests (CrystalDiskMark 3.0.2 and intensive
CHKDSK) don't show up problems. It is only appearing 6 or 12h later.
Do you have any idea on how to prevent it ? Is cache=writethrough an
acceptable solution ? We don't want to leave qcow2 image format as
it does allow to do live snapshots et al.
How are you taking live snapshots? qemu-img should not be used on a
disk image that is currently open by a running guest, it may lead to
corruption.
Stefan
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