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Effective Memory Usage of Reassign Defect Map

IP.com Disclosure Number: IPCOM000117864D
Original Publication Date: 1996-Jun-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Andoh, H: AUTHOR [+4]

Abstract

Disclosed is an effective memory usage of Reassign Defect Map (RDM). RDM has the information of Reassigned Logical Block Address (LBA) and Spare LBA for reassigned LBA. By converting Reassigned LBA to Virtual Track and Virtual Sector and only registering spare offset from MAX LBA, the number of available RDM entry can double approximately with the same memory size.

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Effective Memory Usage of Reassign Defect Map

      Disclosed is an effective memory usage of Reassign Defect Map
(RDM).  RDM has the information of Reassigned Logical Block Address
(LBA) and Spare LBA for reassigned LBA.  By converting Reassigned LBA
to Virtual Track and Virtual Sector and only registering spare offset
from MAX LBA, the number of available RDM entry can double
approximately with the same memory size.

      The memory image is shown in Fig. 1.  Low word of Reassigned
LBA, which is named Virtual Sector, is registered to Reassign Virtual
Sector Table (RVST) in ascending order.  High word is named Virtual
Track.  The accumulated number from previous Virtual Track is
registered to Reassign Virtual Track Table (RVTT).  Offset value from
MAX LBA is registered to Reassign Offset Sector Table (ROST) instead
of Spare LBA for reassigned LBA.  The method of converting to
RVTT/RVST/ROST and decoding from them is described in Fig. 2 with a
sample.  With this conversion method, the RDM entry number can be
increased about two times with the same memory size.

This conversion method can apply to any case using LBA information.