(Alpha and Integrity servers) MPDEV_AFB_INTVL specifies the
    automatic failback interval in seconds. The automatic failback
    interval is the minimum number of seconds that must elapse before
    the system attempts another failback from an MSCP path to a
    direct path on the same device.

    MPDEV_POLLER must be set to ON to enable automatic failback. You
    can disable automatic failback without disabling the poller by
    setting MPDEV_AFB_INTVL to 0. The default is 300 seconds.