The IBM 3850: A mass storage system with disk characteristics

The IBM 3850 is a hierarchical storage system that provides capacities of up to 472 billion bytes and offers disk-access capabilities by use of a virtual direct-access storage concept. The architecture of the system is described in terms of control and data flow within the mass storage system (MSS). An example of tape/disk I/O work load on a current system is analyzed to indicate the data-transfer demand that the major interfaces in the MSS storage hierarchy would face as part of determining an appropriate configuration. The systems control and techniques of space management are also outlined.