Hierarchical storage systems adapted for error handling.

摘要

Data associated with a defective area (18) of a backing store (13) and stored in an alternate area (25), such as defective and alternate tracks in a direct access storage device, is pinned to a high speed buffer front store (14) based upon usage for such data. A first replacement control governs buffer operation for data from good areas of the backing store and a second independent replacement control governs buffer operation for data from alternate storage areas. Limitations are imposed on the amount of data subject to the second replacement control.