Hello, it seems like I have discovered a bug in qemu-0.14.1 which corrupts Qcow2 image files when using internal snapshots. I tied this both on an amd64 host running our Debian bases UCS distribution (using pure qemu-kvm_0.14 and pure qemu-kvm_0.14.1) and also on a pure Debian i386 sid installation (patched qemu-kvm_0.14.1). I can reproducte this every time doing the following steps: 0. Create and install VM 1. Shut down VM 2. Create offline snapshot using "qemu-img snapshot -c Off image.qcow2" 3. Start VM 4. Create online snapshot using "savevm On" 5. Shut down VM 6. Revert to snapshot using "qemu-img snapshot -a Off image.qcow2" Repeat step 6 three or more times and the Image is destroyed. My guess is that this is a but in qemu-img, which is related to having an online snapshot (VM running) while reverting to an offline snapshot (VM stopped), because I wasn't able to reproduce this using only offline snapshots or only online snapshots. I have attached a shell script to reproduce this bug on all my runs. * It both happens with kvm-0.14.1 and also with qemu-0.14.1. * The cache stragtegy "writethrough" vs. "writeback" is irrelevant. The script needs an image nameded "pmh_squeeze-0.qcow.bak2" of an VM where you can login via serial console using "root" for login and "univention" for password. You can use other images as well, as long as you modify the block device from within the VM. You get get it from <http://download.univention.de/download/temp/qemu-0.14-qcow2/> There you will also find the beginning of a small Python program called "qcow2.py" which can be used to dump the structure of an qcow2 file in some more human readable format with some consistency checking. Related links: <http://git.kernel.org/?p=virt/kvm/qemu-kvm.git;a=commit;h=e11480db7ff15a9e878f6b3cc1199b439bf7c825> <http://git.kernel.org/?p=virt/kvm/qemu-kvm.git;a=commit;h=f0aa7a8b2d518c54430e4382309281b93e51981a> <http://lists.gnu.org/archive/html/qemu-devel/2011-04/msg01376.html> <https://forge.univention.org/bugzilla/show_bug.cgi?id=22221> Any help is appreciated. Sincerely Philipp Hahn -- Philipp Hahn Open Source Software Engineer hahn@xxxxxxxxxxxxx Univention GmbH Linux for Your Business fon: +49 421 22 232- 0 Mary-Somerville-Str.1 D-28359 Bremen fax: +49 421 22 232-99 http://www.univention.de/
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