Data storage format conversion method and system, data access method and access control apparatus

摘要

A record storage format conversion method and a system which is capable of mitigating a load imposed on the memory by decreasing the number of accesses to the memory for finding out a CKD record of concern upon format conversion of the CKD records into FBA records while allowing the capacity of a memory required for holding the track data to be decreased. All gaps inclusive of inter-record gaps and inter-field gaps are deleted from variable length records of one track recorded in a variable length format employed in an external storage device of a general-purpose computer. The track data thus obtained is divided into management units each of a predetermined size corresponding to an integral multiple of the size of the fixed length block of the fixed length record. Position information indicating the positions of all the variable length records included in the management unit as well as position information indicating relative positions of the variable length records from the start of the track in the variable length format are written, whereon the management unit is divided into fixed length record blocks each having a predetermined fixed block size for storage thereof. Each CKD record holds information indicating the relative position thereof from the start of the track of the CKD format.