Active_IO=max-writes

    Specifies the maximum number of write operations to a backup
    device that the RMU Backup After_Journal command attempts
    simultaneously. This is not the maximum number of write
    operations in progress; that value is the product of active
    system I/O operations and the number of devices being written
    to simultaneously.

    The value of the Active_IO qualifier can range from 1 to 5. The
    default value is 3. Values larger than 3 can improve performance
    with some tape drives.