BUILT-IN DIRECTORY METHOD FOR DATA COMPRESSION OF DIRECT-ACCESS STORAGE DEVICE AND DIRECTORY RECORD

摘要

PROBLEM TO BE SOLVED: To efficiently manage compressed data in a directory access storage device(DASD) by providing a built-in type directory for storing compressed data directory information with plural page entries, plural exception area entries and plural compressed group statistics. SOLUTION: Allocated page length values and sector values used in allocated pages are identified by plural page entries 80. In addition, page indexes and used exception sectors are identified by plural exception area entries 82 including plural bit map means. The total value of allocated sectors, the total value of used sectors and the total value of written pages are identified by plural compressed group statistics 84. Consequently compressed data in the DASD can be efficiently managed.