Hi, Could you please let us know whether this is still a problem and if it isn't, lets close this bug.
In addition, you haven't listed which version of qemu-kvm you are running. I am guessing it is something Ubuntu based based on the version number, but since not all of us are running Ubuntu it would be useful to have more details. Thanks, Jes -- Snapshot usage makes qcow2 image unusable due to large tables https://bugs.launchpad.net/bugs/322602 You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. Status in QEMU: New Bug description: To reproduce with 0.9.1 and svn: - Create a 20G (or some size much greater than system RAM) qcow2 image - Inside VM, install some OS, formatting whole drive - Create snapshot with savevm - Inside VM, reformat and reinstall OS - Create snapshot with savevm [...] Eventually, qemu crashes, then neither qemu-img nor qemu can open the image because memory is exhausted. The reason is that the whole refcount_table is loaded into memory, and this refcount_table has now become much bigger than the size of memory due to each snapshot taken after significant changes to the disk image. The refcount_table really needs to be loaded and used in fixed size chunks to avoid this problem. It will only get worse as typical storage set modifications during work sessions between snapshots outpace the size of system RAM. Alternatively, there needs to be a way to "rollback" a snapshot without loading the whole disk image normally, so that a snapshot which has made the image unusable in this way can be reversed.
