Browse Prior Art Database

Controlling Multitrack References in a Cached Storage System

IP.com Disclosure Number: IPCOM000050914D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Duke, AH: AUTHOR [+2]

Abstract

A direct access storage device (DASD) is coupled to a host via a caching random-access buffer. The host may refer to a plurality of tracks of the DASD in a given command. In such a multitrack reference, the replacement algorithm for replacing data in the cache is modified from the normal referencing control. In the multitrack reference, only the last track of the multitrack reference has its position in the replacement LRU (least recently used) list. All of the intermediate and earlier tracks referenced maintain their present position in the replacement control list.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 78% of the total text.

Page 1 of 2

Controlling Multitrack References in a Cached Storage System

A direct access storage device (DASD) is coupled to a host via a caching random-access buffer. The host may refer to a plurality of tracks of the DASD in a given command. In such a multitrack reference, the replacement algorithm for replacing data in the cache is modified from the normal referencing control. In the multitrack reference, only the last track of the multitrack reference has its position in the replacement LRU (least recently used) list. All of the intermediate and earlier tracks referenced maintain their present position in the replacement control list.

A multitrack access to the cached storage system results in an examination of the cache directory to determine whether or not a cache hit or cache miss occurs. For a hit, data is transferred directly between the cache and the host, as indicated by the double-headed arrow. On a cache miss, data may be transferred (staged) to the cache for later transfer to the host. Alternatively, on a cache miss, all subsequent references to data in the multitrack reference may be directly between the DASD and the host, as indicated by the host-DASD transfer doubleheaded arrow. Once completing transfer of a given track, the track is indexed with the procedure repeated. For a cache miss of any track, all subsequent references to succeeding tracks are treated automatically as a cache miss, until the end of the cylinder or until the end of the multitrack acces...