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Yeah, apparmor's not really installed despite the
/etc/apparmor.d directory being there on account of libvirt adding
it (I guess). Hmm.... On 06/06/2012 05:23 PM, Eric Blake wrote: On 06/06/2012 10:55 AM, Sean Abbott wrote:So, I was attempting to use qemu snapshots with backing stores. The QEMU docs (http://wiki.qemu.org/Documentation/CreateSnapshot) make it sound like you simply point your qemu at the snapshot after it's creation, and you're golden. When attempting this with libvirt, though, it fails.Libvirt definitely supports this, as I use it for my guests, so let's figure out where you went wrong. By the way, libvirt can create qcow2 files itself, rather than forcing you to hand-create it with qemu-img, although support for this could probably be improved with more APIs and documentation. Patches welcome.I created a snapshot using the above tutorial. the resulting file is disk.0, and a qmeu-img info on it returns: image: disk.0 file format: qcow2 virtual size: 29G (31457280000 bytes) disk size: 140K cluster_size: 65536 backing file: /var/lib/one/public/lin_client_current.qcow2 (actual path: /var/lib/one/public/lin_client_current.qcow2) So that all looks groovy, right?Unfortunately, 'qemu-img info' output doesn't say whether you properly populated the backing_fmt property, but I will assume that is not your issue (do note, however, that failure to use the backing_fmt property is a security hole - it means libvirt and/or qemu will autoprobe the format from the backing file itself, but if the backing file is supposed to be raw, the guest can manipulate the backing file into looking non-raw, and cause your host to hand over control of files to the guest that should not normally be accessible to the guest).Then, I created (via opennebula) an xml deployment file like so: http://paste.ubuntu.com/1027145/which included: <disk type='file' device='disk'> <source file='/var/lib/one/vm/56/images/disk.0'/> <target dev='hda' bus='virtio'/> <driver name='qemu' type='qcow2' cache='none'/> and that looked correct to me.When I attempt to do a virsh create, I get the following errors: virsh # create deployment.0 error: Failed to create domain from deployment.0 error: internal error process exited while connecting to monitor: file=/var/lib/one/vm/56/images/disk.0,if=none,id=drive-virtio-disk0,boot=on,format=qcow2,cache=none qemu-kvm: boot=on|off is deprecated and will be ignored. Future versions will reject this parameter. Please update your scripts.This warning is not the real problem, but a patch to libvirt to avoid it might be nice, if it hasn't already been patched in newer libvirt.qemu-system-x86_64: -drive file=/var/lib/one/vm/56/images/disk.0,if=none,id=drive-virtio-disk0,boot=on,format=qcow2,cache=none,boot=on: could not open disk image /var/lib/one/vm/56/images/disk.0: Invalid argumentYou mentioned Ubuntu - do you have appArmor running? This could be a case of the apparmor settings on your machine preventing qemu from opening the backing file. I don't have Ubuntu experience myself to tell you how to resolve it (I tend to work with SELinux on Fedora as my security mechanism), but suspect that it might be a failure along the lines of an over-strict security policy.So...something isn't working. Is it possible to do this, or should I give up on this path?Libvirt definitely supports what you want to do, but I don't know what to suggest to help you get further. |
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