VMS Help EXCHANGE, INITIALIZE, Qualifiers, /BADBLOCKS  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /BADBLOCKS[=RETAIN]

    Performs a bad block scan of the volume before initialization. A
    file named FILE.BAD is created on top of each bad block or group
    of bad blocks encountered on the device, preventing any future
    use of the bad areas.

    If a bad block is found in either the boot block or the volume
    directory, the volume is not usable and EXCHANGE displays
    an error message. If the bad block is in a directory segment
    other than the first, you might be able to use the volume by
    reinitializing it with a smaller number of segments (see the
    /SEGMENTS qualifier description).

    If you specify /BADBLOCKS=RETAIN, EXCHANGE uses the device's
    existing bad block information, instead of performing a bad block
    scan. Therefore, initializing takes less time. If you do not
    specify RETAIN, EXCHANGE writes a pattern on each block of the
    volume, then reads each block to verify that the block is usable.
    EXCHANGE prints a list of the bad blocks found on the device.

    RK06, RK07, and RL02 disk volumes support bad block replacement.
    Therefore, Compaq recommends that you use the /REPLACE=RETAIN
    qualifier for these volumes. If you use the /BADBLOCKS qualifier
    with a volume initializied previously with the /REPLACE
    qualifier, EXCHANGE deletes the bad block replacement table and
    performs a new bad block scan. If you use /BADBLOCKS=RETAIN with
    such a volume, EXCHANGE uses the FILE.BAD files created during
    the volume initialization.