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Improving Data Integrity in a Storage Hierarchy

IP.com Disclosure Number: IPCOM000050550D
Original Publication Date: 1982-Nov-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 58K

Publishing Venue

IBM

Related People

Duke, AH: AUTHOR [+3]

Abstract

For enhancing operations, storage hierarchies often have a volatile buffer coupled to a lower performance retentive store. The integrity of the data stored in the volatile buffer is subject to power perturbations. When a user supplies data to the storage hierarchy (write) and no space is allocated in the volatile buffer, then the data is sent directly to the retentive store; otherwise, the data is written to the buffer, then to the retentive store. In accordance with this operation, the number of times that a user writes data to the storage hierarchy, where space is allocated in the volatile buffer for such data, is minimized for ensuring writing directly to the retentive store to the exclusion of the buffer.

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Improving Data Integrity in a Storage Hierarchy

For enhancing operations, storage hierarchies often have a volatile buffer coupled to a lower performance retentive store. The integrity of the data stored in the volatile buffer is subject to power perturbations. When a user supplies data to the storage hierarchy (write) and no space is allocated in the volatile buffer, then the data is sent directly to the retentive store; otherwise, the data is written to the buffer, then to the retentive store. In accordance with this operation, the number of times that a user writes data to the storage hierarchy, where space is allocated in the volatile buffer for such data, is minimized for ensuring writing directly to the retentive store to the exclusion of the buffer. In a peripheral system, characterized by chains of commands, each chain of command is monitored with the characteristic of the operation performed during that chain being logged. Before a subsequent chain of operations for a related set of commands is performed, data is selectively demoted from the volatile buffer to the retentive store for encouraging write misses. Such demotion is based upon signals received from the host indicating a low likelihood of reuse of the data based upon characteristics of the operations being performed by the host which indicate a low likelihood of immediate reuse.

A host or user accesses the storage hierarchy through a volatile buffer coupled to the retentive store. A control for the storage hierarchy controls the data transfers between the volatile buffer and the retentive store, tending to store data in the volatile buffer to be next accessed by the host or user. The control also provides for selectively bypassing the volatile buffer such that the host or user can directly access the retentive store.

In a first sequence of operation, a user writes to the storage hierarchy the results in a check to see whether or not the space is allocated in the volatile buffer. When space is allocated, a hit (no miss) occurs, resulting in a write to the volatile buffer followed by a write to the retentive store. For a miss occurring, the user writes directly to the retentive store. This procedure ensures a maximal data integrity in the storage hierarchy. Such procedure indicates that misses during write operations should be encouraged. This is done asynchronously to the host or user accesses intermediate a series of chains of operations, as described in the next paragraph.

A chain of operations characterized by a chain of commands from the host directed to the storage hierarchy results in a plurality of operations being performed. These operations are monitored in the storage hierarchy and logged as LOGOPS, which indicate the characteristics of operations conducted in the chain of operations as well as any signals including the particular commands received from the host during the chain of operations, such as these LOGOPS are used intermediate chains of operatio...