On 01/30/2015 04:57 AM, Fabrizio Soppelsa wrote:
Hello,
what happens when an instance writes data with 0% available physical disk space, on QCOW2 images for instance, apart from destruction and unpredictability? I'm aware that monitoring is mandatory in production environments, but are there other known industry tricks to deal with this? Soft/hard limit settings, autopause/stop, or does KVM react in doing force shut down the VM in question?
It's possible to run your guest with I/O error reporting - if the host runs out of space for qemu to write to the qcow2 file, then the guest is paused and a qemu event is raised (which in turn can be transmitted as a libvirt event); if you then give the host more storage and resize the disk, you can resume the guest, and the guest has no idea that there was a transient storage shortage in the host other than the fact that a lot of wall clock time elapsed for one operation. Look for the 'error_policy' XML setting under http://libvirt.org/formatdomain.html#elementsDisks -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org