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Improving Direct Access Storage Device Reclaim

IP.com Disclosure Number: IPCOM000040126D
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-01

Publishing Venue

IBM

Related People

Authors:
Crowley, TR Sparrow, SS [+details]

Abstract

The use of a displacement field in the alternate sector ID of a disk data storage device permits a reclaim program to more efficiently compute the Physical address of the primary sector associated with the alternate sector to reclaim. A direct access storage device (DASD) unit consists of multiple cylinders. Each cylinder contains multiple heads which access multiple sectors. Each sector consists of an ID field and a data field. The format of the ID field is as follows: (Image Omitted) BYTE Bit Field ---- --- ----- 0 0-2 Displacement amount 0 3 Reassigned (1=yes) 0 4 Alternate (1=yes) 0 5-6 Defect flags 0 7 Reserved 1-3 Logical address (Head, cylinder, sector).