/MV_NUM=n

    Overrides the system-wide setting of the MVSUPMSG_NUM system
    parameter with the value specified by n (seconds) for the
    specified device only. If /MV_NUM=0, the value for MVSUPMSG_NUM
    is used instead. If MVSUPMSG_NUM=0 or MVSUPMSG_INTVL=0, all mount
    verifications are announced. For more information about MVSUPMSG_
    NUM, see Sys_Parameters online help.