1. A method of operating a computer system to stripe file data across a plurality of attached disk storage devices, the computer system having means for writing data to the disk storage devices, run time environment means and means for executing programs containing control statements for defining file names in the run time environment means and containing object code including file open statements, comprising the steps of: detecting the execution of an open statement in the object code; querying the run time environment for a definition of a preselected file name and if the preselected file name has been defined in the run time environment performing the following steps: selecting a number (N), greater than one, of stripes if the preselected file name has been defined in the run time environment, the number being derived from the preselected file name; and striping file data associated with the open statement by dividing the file data into N blocks and writing the N blocks to N disk storage devices in parallel.