Off-Track Data Rewrite in Shingled Magnetic Recording
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Solution Overview
Problem
In magnetic disk devices, data misalignment during shingled write recording leads to deteriorated read performance on adjacent tracks, making it difficult to rewrite data without stopping the writing process and requiring additional buffer storage, resulting in delays.
Innovation Solution
Implementing a configuration where data is written from the inner side to the outer side of a track group, using a buffer to store data from adjacent tracks and writing it into subsequent sectors if the head is misaligned, and registering misaligned sectors as provisional defect sectors to allow continued writing without interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the head rewrites data into the adjacent track to prevent read performance deterioration, then data reliability is improved, but the head must move to the adjacent track causing delay
Solution Approach 1:
The patent applies preliminary action by detecting off-track writing conditions during the normal writing process and proactively rewriting data to subsequent sectors before the head completely loses alignment. The determination unit identifies when the head is off the target track, and the rewrite unit immediately corrects the data in subsequent sectors, preventing read performance deterioration without requiring the head to move back to the adjacent track after completion.
2Reliability
If the same data is rewritten into the adjacent track, then data reliability is improved, but additional buffer storage is required resulting in delay
Solution Approach 1:
The patent extracts the data rewriting operation from the adjacent track and relocates it to subsequent sectors on the current track. By determining that the head is off the target track and rewriting data to sectors that will be written to anyway during the current writing sequence, the system eliminates the need for additional buffer storage that would be required if rewriting to the adjacent track, thus reducing device complexity while maintaining data integrity.
3Reliability
If the head moves to the adjacent track for rewriting, then data reliability is improved, but the writing process must be stopped causing delay
Solution Approach 1:
The patent ensures continuity of useful action by performing the data rewriting operation during the ongoing writing sequence without interruption. The determination unit continuously monitors head position, and when off-track writing is detected, the rewrite unit immediately corrects data in subsequent sectors that will be written to during the current sequence. This eliminates the need to stop the writing process for rewriting operations, maintaining continuous productivity while ensuring data reliability.
Data Source
AI summary
According to one embodiment, an information recorder includes: a determination module; a storage module; a reader; and a writer. The determination module determines whether a position of a head for writing data is off a target track of a recording medium. The storage module temporarily stores therein data written by the head. The reader reads, if it is determined that the head is positioned off the target track, first data written in a sector which is considered overwritten by the head positioned off the target track among sectors of an adjacent track adjacent to the target track, from the storage module. The writer writes, if it is determined that the head is positioned off the target track, the first data into a sector positioned later than the sector into which data is written at the time the head is positioned off the target track.