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Using DASD Scan Results to Improve DASD Save Operations

IP.com Disclosure Number: IPCOM000039983D
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

Verifying the readability of DASD (direct access storage device) sectors before attempting to save DASD data improves the performance of a Save operation. The Save operation does not waste time running error recovery procedures on sectors which a Scan operation has already identified as containing uncorrectable errors. (Image Omitted) A procedure (hereafter referred to as a Scan operation) executes a 'verify' command on each sector of the DASD unit (Fig. 1). The 'verify' command response data indicates if a sector has an error and the type of the error (correctable or uncorrectable). The 'verify' command does not transfer the DASD data into mainstore, and executes many times faster than a 'read-data' command. The results of the Scan operation are placed in a table (referred to as the Scan-Table).