Disk and File Utilities (DFU) is a high performance utility
 developed to perform routine maintenance and special purpose
 operations on ODS-2 disk volumes, files and directories. The
 functionality offered by DFU is not or partly available through
 other DCL commands or VMS utilities. Minimal support for some ODS-5
 file information is provided.
    DFU has the following functions:

    Command            Description

    DEFRAGMENT         defragment individual files or an entire disk
    DELETE             delete files by file-id, and delete
                       directory(trees) fast
    DIRECTORY          COMPRESS, DUMP or RECOVER directories, search
                       directories for files with multiple versions,
                       alias files, or empty directories
    INDEXF             analyze, defragment truncate and extend
                       INDEXF.SYS
    REPORT             reports disk fragmentation
    REVERSION          reversions files back to starting at ;1
    SEARCH             search for files
    SET                set file attributes
    UNDELETE           recover deleted files
    VERIFY             analyze (and repair) the disk structure