The Verify option provides a function equivalent to ANALYZE/DISK,
 but many times faster. Verify will report files with invalid backlinks,
 lost files, and blocks which are allocated by more than 1 file. Also the
 BITMAP and QUOTA files are checked. The /FIX qualifier allows some
 basic repair actions without locking the disk. The /REBUILD qualifier
 will rebuild INDEXF.SYS, BITMAP.SYS and QUOTA.SYS if necessary.
 Note that /REBUILD will lock the disk for a short period of time.

 Syntax :

 	VERIFY <device>(/OUTPUT=<filename>/LOCK/FIX/REBUILD)

1  –  Qualifiers

1.1    /APPEND

     /APPEND=filename

    Same as /OUTPUT, but the output will be appended to the
    file if it already exists. Thus output from multiple
    DFU commands can be put in the same output file.
    If the file does not exists it will be created.

1.2    /DIRECTORY_SCAN

    This optional qualifier directs DFU to make a full directory
    scan. This allows better detection of some cases of lost
    files, and detection of some directory corruptions. Use
    /FIX to repair such errors.

    Warning: using /DIRECTORY_SCAN can take several minutes

1.3    /FIX

    /FIX
    /NOFIX (default)

    This qualifier repairs the following errors:

    o Deletes files marked for delete
    o Moves lost files and directories to [SYSLOST]
    o Repairs a wrong backlink for VMS$COMMON.DIR (system disk)

    The /FIX qualifier does not lock the disk!

1.4    /LOCK

    /LOCK
    /NOLOCK (default)

    Locks the volume for allocation. To get a consistent view of the disk
    one must stall all allocation changes of the disk. Otherwise VERIFY
    may report errors which are caused by concurrent disk activity during
    execution of the VERIFY command. Trade off is that the disk is locked
    for the duration of the VERIFY command.

1.5    /OUTPUT

    Redirects the output from verify to a file.

1.6    /REBUILD

    /REBUILD
    /NOREBUILD (default)

    This qualifier repairs structure errors and mismatches in
    INDEXF.SYS, BITMAP.SYS and QUOTA.SYS. Note that /REBUILD
    will temporarily lock the device for other users.

1.7    /STATISTICS

    /STATISTICS
    /NOSTATISTICS (default)

    Controls whether cpu and I/O consumption of the
    command are shown.