IBM this week formally introduced the first of the products that make up the company’s Supercomputing Systems Extensions, which were pre-announced by the company on May 30. The product, which promises to be important in the company’s mainstream operations as it moves over to disk striping techniques – storing one bit from each byte of data on a different platter and accessing them in parallel – is the Parallel Input-Output Access Method program and provides high-speed data access to 3380 and some non-disk storage devices. The new access method is designed to meet the needs of engineering, scientific, and real-time applications in which input-ouput service time is a significant factor in overall performance, IBM says. The higher speed is achieved by using multiple input-output paths in parallel as well as by optimising access along individual data paths. The Parallel Input-Output Access Method is a set of subroutines for both direct and sequential processing, and provides rapid access to a single file by scattering consecutive records across multiple devices and data paths. IBM calls the technique file striping, and the improvement in speed can equal the number of devices and the number of input-output paths used in parallel to hold a file and it can specify the level of parallelism up to 255 when a file is created. It supports fixed length records and data access to files by using relative record numbers. Multiple input-output requests can be queued under program control so that multiple data requests can be satisfied in a single channel program. It reads and writes data to and from user-defined areas, which can be placed above the 16Mb line for virtual storage constraint relief, and a high-level program interface shields system complexity from the application programmer for Fortran and Assembler. Support for devices other than disk is provided by Intel Corp’s 9770 high-speed channel. The Paral lel Input-Output Access Method is designed to run on any IBM processor that supports MVS/XA or MVS/ESA and supports all models of the 3380 currently available and the 3880 and 3990 disk controllers. The Parallel Input-Output Access Method $25,000 and is due on November 10 in the US.
