Threads=number

    Specifies the number of reader threads to be used by the copy
    process.

    RMU creates so called internal 'threads' of execution to read
    data from one specific storage area. Threads run quasi-parallel
    within the process executing the RMU image. Each thread generates
    its own I/O load and consumes resources like virtual address
    space and process quotas (e.g. FILLM, BYTLM). The more threads,
    the more I/Os can be generated at one point in time and the more
    resources are needed to accomplish the same task.

    Performance increases with more threads due to parallel
    activities which keeps disk drives busier. However, at a certain
    number of threads, performance suffers because the disk I/O
    subsystem is saturated and I/O queues build up for the disk
    drives. Also the extra CPU time for additional thread scheduling
    overhead reduces the overall performance. Typically 2-5 threads
    per input disk drive are sufficient to drive the disk I/O
    susbsystem at its optimum. However, some controllers may be
    able to handle the I/O load of more threads, for example disk
    controllers with RAID sets and extra cache memory.

    In a copy operation, one thread moves the data of one storage
    area at a time. If there are more storage areas to be copied than
    there are threads, then the next idle thread takes on the next
    storage area. Storage areas are copied in order of the area size
    - largest areas first. This optimizes the overall elapsed time
    by allowing other threads to copy smaller areas while an earlier
    thread is still working on a large area. If no threads qualifier
    is specified, then 10 threads are created by default. The minimum
    is 1 thread and the maximum is the number of storage areas to be
    copied. If the user specifies a value larger than the number of
    storage areas, then RMU silently limits the number of threads to
    the number of storage areas.

    For a copy operation, you can specify a threads number as low as
    1. Using a threads number of 1 generates the smallest system
    load in terms of working set usage and disk I/O load. Disk
    I/O subsystems most likely can handle higher I/O loads. Using
    a slightly larger value than 1 typically results in faster
    execution time.