Modern computer systems have been built around the assumption that persistent storage is accessed via a slow, block-based interface. However, new byte-addressable, persistent memory technologies such as Phase Change Memory (PCM) offer fast, fine-grained access to persistent storage. In this paper, the authors present a file system and a hardware architecture that are designed around the properties of persistent, byte addressable memory. Their file system, BPFS, uses a new technique called short-circuits shadow paging to provide atomic, fine-grained updates to persistent storage. As a result, BPFS provides strong reliability guarantees and offers better performance than traditional file systems, even when both are run on top of byte-addressable, persistent memory.