1. An operating system-independent file map generator for generating an operating system-independent map of a file stored on a mass storage subsystem, the mass storage subsystem storing data in a series of blocks, the file being stored on a least device extent comprising at least one block, the generator comprising: A. a file identifier receiver for receiving a file identifier for the file; B. a query module for querying a disk extent manager to obtain disk extent information for the file identified by the file identifier, the disk extent information identifying the at least one extent; and C. a file map entry generator for generating a file map entry for the file map for the file, the file map entry including the disk extent information obtained by the query module.