The solution I came up with was to go to cd /var/lib/nova/instances/, choose my instance id, and run qemu-img commit -f qcow2 disk. This process takes a long time, a little over 24 hours, and requires me to take down my instances whenever my backup time gets to long. After I did this my instance that was taking 21 hours to backup took two and a half hours. Is there a way to prevent image_pending_upload from growing so large?