/WINDOW=[FULL]LIMITED

    Specifies the number of mapping pointers to be allocated for file
    windows. By default, file window has 7 mapping pointers and it
    increases as file is more fragmented. Window is taken from nonpaged
    pool and is charged against process BYTLM quota. This may result
    in performance degrade when BACKUP tries to map the 8th extent
    of the file. Contiguous files are always completely mapped, but
    noncontiguous files may or may not be completely mapped.

    You can use the following keywords with the /WINDOW qualifier:

    FULL        Default full mapping.
    LIMITED     Optional limited size window.