Browse Prior Art Database

Twin Storage Used for High Speed Store Protection

IP.com Disclosure Number: IPCOM000081984D
Original Publication Date: 1974-Sep-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Murphy, CA: AUTHOR [+2]

Abstract

Large-scale integration (LSI) raises new problems on techniques of handling storage protection and data security. In the past, central processing units have usually been fast compared with storage, and storage protection was handled by small fast arrays in the central processing units.

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Twin Storage Used for High Speed Store Protection

Large-scale integration (LSI) raises new problems on techniques of handling storage protection and data security. In the past, central processing units have usually been fast compared with storage, and storage protection was handled by small fast arrays in the central processing units.

In LSI, the CPU and storage may use the same technology and run at the same speed. This causes a performance degradation by delaying the write cycle when using a conventional storage protect technique. To prevent degradation of performance using storage protect, two copies of storage can be used. The two storages can be at any hierarchical level - storage #2 holds a copy of the information that is being modified in storage #1, while the storage protect keys and locks are being examined. One true copy is always preserved in storage #2, should the data not have been modified because keys and locks did not match. The match check is not completed until after the data was modified so that the CPU cycle will not be slowed down. The storage that contains the valid data writes it into the storage that was made invalid whenever time is available.

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