Abstract: A system and method for remote asynchronous replication or mirroring of changes in a source file system snapshot in a destination replica file system using a scan (via a scanner) of the blocks that make up two versions of a snapshot of the source file system, which identifies changed blocks in the respective snapshot files based upon differences in volume block numbers identified in a scan of the logical file block index of each snapshot. Trees of blocks associated with the files are traversed, bypassing unchanged pointers between versions and walking down to identify the changes in the hierarchy of the tree. These changes are transmitted to the destination mirror or replicated snapshot. This technique allows regular files, directories, inodes and any other hierarchical structure to be efficiently scanned to determine differences between versions thereof.

Abstract: A devtmp device driver provides the functionality of temporary files by representing a virtual device and including the virtual device among several devices within which a file system can store files. Rather than storing data in and retrieving data from a physical device, the devtmp device driver stores data in and retrieves data from anonymous storage through a swap file system which manages anonymous storage for a virtual memory system. A file system uses the devtmp device driver in the same manner the file system uses conventional device drivers which store data in and retrieve data from secondary storage devices. Since the devtmp device driver represents a virtual device whose data are stored in anonymous storage managed by the swap file system, the total amount of storage available for storing data of temporary files is shared among the various components of a computer process to successfully satisfy various needs of various computer processes.