This tutorial explains how you can revert failed apt operations (like apt-get upgrade) and roll back to the previous system state with apt-btrfs-snapshot on an Ubuntu 12.10 system that uses the btrfs file system. apt-btrfs-snapshot creates a snapshot of the system before the apt operation. Being able to easily restore the previous system state after a failed apt operation takes away much of the pain system administrators have to deal with normally and is one of the greatest features of the btrfs file system.