Virtual Storage Access Method(VSAM) An {IBM} disk file storage scheme first used in {S/370} and virtual storage. VSAM comprises three access methods: {Keyed Sequenced Data Set} (KSDS), {Relative Record Data Set} (RRDS), and {Entry Sequenced Data Set} (ESDS). Both {IMS/DB} and {DB2} are implemented on top of VSAM and use its underlying data structures. ["Storage" or "Sequential"?] (2002-07-26)