def METHOD_NAME(self):
    """This will read the storage device from disk."""
    import csv
    f = open(self._get_db_name())
    vals = csv.DictReader(f, _field_names)
    db = {}
    for v in vals:
        db[v.pop("hash")] = v
        if v["last_seen"] is None:
            v["last_seen"] = 0.0
        else:
            v["last_seen"] = float(v["last_seen"])
    f.close()
    return db