A FAST, HIGHLY RELIABLE DATA-COMPRESSION CHIP AND ALGORITHM FOR STORAGE-SYSTEMS

Data compression allows more efficient use of storage media and commun ication bandwidth, and standard compression offerings for tape storage have been well established since the late 1980s. Compression technolo gy lowers the cost of storage without changing applications or data ac cess methods. The desire to extend these cost/performance benefits to higher-data-rate media and broader media forms, such as DASD storage s ubsystems, motivated the design and development of the IBMLZ1 compress ion algorithm and its implementing technology. The IBMLZ1 compression algorithm was designed not only for robust and highly efficient compre ssion, but also for extremely high reliability. Because compression re moves redundancy in the source, the compressed data become extremely v ulnerable to data corruption. Key design objectives for the IBMLZ1 dev elopment team were efficient hardware execution, efficient use of sili con technology, and minimum system-integration overhead. Through new o bservations of pattern matching, match-length distribution, and the us e of graph vertex coloring for evaluating data flows, the IBMLZ1 compr ession algorithm and the chip family achieved the above objectives.