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

       /POLICY=[NO]MINICOPY[=(OPTIONAL)]

    Controls the setup and use of the shadowing minicopy function.

    The exact meaning of the MINICOPY keyword depends on the context
    of the DISMOUNT command, as follows:

    1. If this is a dismount of a single member from a multi-member
       shadow set, a write bitmap is created to track all writes
       to the shadow set. This write bitmap may be used at a later
       time to return the removed member to the shadow set with a
       minicopy.

       If the write bitmap cannot be initiated and the keyword
       OPTIONAL is not specified, the dismount will fail and the
       member will not be removed.

       If you omit the /POLICY qualifier or if you specify
       /POLICY=NOMINICOPY, no bitmap will be created.

    2. If this is the final dismount of the shadow set in the
       cluster, the shadow set is verified to be capable of a future
       minicopy operation.

       If the shadow set has only one member or is in a merge state,
       and if OPTIONAL was not specified, the dismount will fail.

       Specifying neither NOMINICOPY nor MINICOPY is the same as
       MINICOPY=OPTIONAL, as the set will be dismounted regardless of
       the prior checks.

    For additional information, refer to Volume Shadowing for
    OpenVMS.