/ENABLE=HBMM
       /ENABLE=SPLIT_READ_LBNS

    /ENABLE=HBMM enables host-based minimerge (HBMM) on the
    specified shadow set or across the entire cluster if an
    applicable HBMM policy exists. This value applies to HBMM
    operations only. If you specify any non-HBMM qualifiers
    with this value, the command will fail.

    /ENABLE=SPLIT_READ_LBNS logically divides the shadow set members
    having the same read cost into equal groups of Logical Block
    Numbers (LBNs). When a virtual unit performs a read, it does so
    by reading from the corresponding LBN group. This results in the
    maximum usage of the controller read-ahead cache. To learn more
    about HBMM policies and their application, see the VSI Volume
    Shadowing for OpenVMS manual.