This command causes EFI$CP to access and to read in data
    structures needed for processing the FAT disk volume.

    For EFI partition files such as SYS$LOADABLE_IMAGES:SYS$EFI.SYS
    and SYS$MAINTENANCE:SYS$DIAGNOSTICS.SYS, you can use software
    such as the OpenVMS LD component to render the partition file
    accessable as a (usually foreign-mounted) disk device.

    If the volume FAT data is found corrupted, MOUNT will attempt
    to read the FAT data from a shadow copy of the FAT sector. Most
    FAT volumes have two copies of FAT data present, and MOUNT will
    attempt to use all available copies upon receipt of FAT I/O
    failures within the FAT data.

    MOUNT does not compare the FAT data across copies of the FAT upon
    successful I/O operations. Comparison is not attempted as with
    typically only two copies of FAT data present, and as there is no
    checksumming and no ECC within FAT, there is no way to determine
    which copy of the FAT is correct. EFI$CP does write modified data
    to all copies of the FAT present

    Should MOUNT detect sector read I/O errors in all copies of a
    FAT sector, MOUNT will synthesize a block of FAT EOC (End of
    Cluster Chain) markers to replace the missing FAT data, and will
    continue with the MOUNT attempt. This EOC sector will effectively
    truncate any files using cluster chain data stored within the bad
    FAT sector, but may allow access to other files and to parts of
    any files that reference (valid) cluster chain data prior to that
    stored within the failed sector. Should this recovery processing
    be triggered, you will obviously want to immediate relocate all
    remaining data onto other media.

    Mount can also check the integrity of the files when /CHECK
    or /REPAIR are specified in the command. If the volume was
    not cleanly dismounted, the check will be done unless the user
    explicitly uses /NOCHECK. Some older versions of EFI$CP may have
    created files with incorrect lengths which show up as errors in
    EFICHK (a utility in the VMS UTILITIES area that can be run from
    the EFI command shell). If EFI$CP detects that the FAT volume was
    created with an old version of EFI$CP, it will automatically
    check and repair the volume (unless /NOWRITE or /NOCHECK is
    specified) and update the volume information to the current
    version of EFI$CP.