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Isolation of Buffer to Backing Storage Errors With a Swapping Buffer Replacement Algorithm

IP.com Disclosure Number: IPCOM000078622D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 3 page(s) / 45K

Publishing Venue

IBM

Related People

Glick, EW: AUTHOR [+4]

Abstract

A technique is provided for assigning buffer to backing storage data errors to the proper task, when a swapping replacement algorithm is utilized. The buffer and backing storage hierarchy provides an arrangement in which the buffer storage has a relatively lower storage capacity than that of the backing storage, but operates at a relatively higher speed. Thus, copies of data stored in the backing storage may be maintained in the buffer storage and be available at a much higher speed than would be from backing storage.

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Isolation of Buffer to Backing Storage Errors With a Swapping Buffer Replacement Algorithm

A technique is provided for assigning buffer to backing storage data errors to the proper task, when a swapping replacement algorithm is utilized. The buffer and backing storage hierarchy provides an arrangement in which the buffer storage has a relatively lower storage capacity than that of the backing storage, but operates at a relatively higher speed. Thus, copies of data stored in the backing storage may be maintained in the buffer storage and be available at a much higher speed than would be from backing storage.

Initially, buffer storage is empty and when a storage fetch request is made, a block of data is transferred from the backing storage to the buffer storage. Subsequent requests to store or fetch data from the block will now be satisfied by accessing buffer storage only. When a subsequent request is made to access another block not resident in buffer storage, a block transfer operation is again performed to make the block resident in another portion of buffer storage. In a multi-task operating system different tasks may, in a similar manner, cause subsequent block transfers to be performed.

Eventually, buffer storage may become fully loaded and an active task storage request may be made to access still another block, which is not resident in buffer storage. Under such circumstances, a block swapping replacement algorithm is utilized, i.e. a block presently resident in buffer storage may have to be swapped or replaced by the block being called for from the backing storage by the active task. This requirement is necessary when the copy of the block, resident in buffer storage, which is to be replaced, has been modified since it was copied from the backing storage, i.e. it is at a later level than the copy in backing storage.

The block of data transferred from the buffer storage to the backing storage may be associated with a diff...