I have a Lenovo ThinkPad T430 running Red Hat Enterprise Linux 6.7, kernel 2.6.32 and QEMU-KVM 0.12.1 (per corporate policy I am not allowed to run a more cutting-edge distribution or any more recent packages). For a training workshop I have to use a QEMU-KVM VM with a qcow2 drive image started directly via the QEMU executable, without virt-manager, and every now and then I need to save my VM's state to disk. However, issuing
savevm <snapshot name> on my VM's monitor console is extremely slow -- saving a snapshot with merely 2 GB of RAM takes easily about 10 minutes or more. I already made sure to check that I'm using
cache=writeback on my virtual HD.
I've read online that the workaround is to use
cache=unsafe, but I'm worried about having my disk image corrupt should my QEMU executable crash or my laptop lose battery power.
Is there any way to make faster QEMU VM snapshots outside of moving them to a faster drive?