Re: [libvirt-users] qemu-img snapshot on running virtual machine

Yes, having two processes (in this case, the qemu process under libvirt's control, and the qemu-img process) both trying to write to a single qcow2 file at once is a recipe for disaster.  You are VERY likely to cause irreparable disk corruption; although at least newer qemu/qemu-io binaries now use file locking to at least fail up front when they detect that another process has the image open for writing, rather than letting you shoot yourself in the foot. The only SAFE way to take a snapshot of a running virtual machine is through commands issued to the qemu process that is running the machine (that is, via libvirt APIs if libvirt is managing the qemu process).