VMS Help Sys Parameters, SWPRATE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    SWPRATE sets the swapping rate (in 10-millisecond units).
    This parameter limits the amount of disk bandwidth consumed by
    swapping.

    This special parameter is used by Compaq and is subject to
    change. Do not change this parameter unless Compaq recommends
    that you do so.