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Data Recovery in a File When File Index Has I/O Errors

IP.com Disclosure Number: IPCOM000046955D
Original Publication Date: 1983-Sep-01
Included in the Prior Art Database: 2005-Feb-07

Publishing Venue

IBM

Related People

Authors:
Yu, MK Chang, PY Stokes, EJ [+details]

Abstract

When a sequential access method recovery routine finds an input/output error in a diskette table of contents, it will delete the index block that is in error. The data referenced by the index block will then become completely inaccessible. However, when the file recovery method scans the data, it is necessary for the file recovery method to know where the data is lost. The file recovery method also needs to post a message to tell the user where the data is lost. It is therefore necessary for the file recovery method to be able to find where the index blocks are deleted. With reference to the figure, when the sequential access method deletes any index blocks, a marker bit in the previous index block is set to indicate that the next block is deleted.