Primary and secondary data processing systems are coupled via a communication system. Data storage in both systems is provided by a log structured array (LSA) system that stores data in compressed form. Each time data are updated within LSA, the updated data are stored in a data storage location different...http://www.google.se/patents/US5555371?utm_source=gb-gplus-sharePatent US5555371 - Data backup copying with delayed directory updating and reduced numbers of DASD accesses at a back up site using a log structured array data storage
