VSAM
VSAM (Virtual Storage Access Method) is an IBM mainframe database management system that provides high-performance access to data stored on direct access storage devices (DASD). It organizes data into datasets with key-sequenced, entry-sequenced, or relative record structures, optimized for fast retrieval and efficient storage management in z/OS environments. VSAM is widely used in legacy enterprise applications for handling large volumes of transactional data.
Developers should learn VSAM when working on IBM mainframe systems, particularly for maintaining or modernizing legacy business applications in industries like banking, insurance, and government. It is essential for tasks involving batch processing, online transaction processing (OLTP), and data management where high-speed access to indexed or sequential files is required, often in COBOL or PL/I programs.