Data Storage Adjacent Track Rewrite Scheduling
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Solution Overview
Problem
In data storage devices, off-track errors during writing data lead to increased probability of vibration-induced errors and performance drops due to continuous rewrite processes on adjacent tracks, which can result in further off-track writing and decreased drive performance.
Innovation Solution
A data storage device with a control circuit that detects off-track errors, assesses potential impact on adjacent tracks, and schedules rewrite requests differently from write retries, using a rewrite request table to manage and execute these requests at optimal timing, thereby minimizing interference and performance drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rewrite processing is continuously executed after write retry, then data integrity on adjacent tracks is improved, but drive performance deteriorates and off-track errors increase
Solution Approach 1:
The patent implements periodic action by suspending rewrite processing for a predetermined period after detecting an off-track error during write retry. This timing-based control allows the system to avoid continuous rewrite operations that cause performance degradation and vibration-induced off-track errors, while still ensuring data integrity by executing the rewrite operation after the suspension period elapses.
2Reliability
If rewrite processing is continuously executed after write retry, then data integrity on adjacent tracks is improved, but the probability of off-track errors increases
Solution Approach 1:
The patent applies preliminary anti-action by proactively suspending rewrite processing immediately after detecting an off-track error. This preliminary suspension prevents the system from entering a state where continuous rewrite operations would exacerbate vibration and increase the probability of further off-track errors, thereby counteracting the harmful effect before it can propagate.
3Reliability
If rewrite processing is continuously executed after write retry, then adjacent track data is corrected, but execution time increases
Solution Approach 1:
The patent implements periodic action by introducing a predetermined suspension period between write retry and rewrite processing. This timing control optimizes command execution time by avoiding unnecessary continuous rewrite operations during the suspension period, while still ensuring adjacent track data correctness by executing the rewrite operation after the suspension period elapses.
Data Source
AI summary
A data storage device, that stores write data by a head, rewrites data on an adjacent track at a timing which is different from write retry of detecting a head off track when data may be written to an adjacent track. When an off track error, which affects data on an adjacent track, is generated by a write command, rewrite processing of this write command is not executed immediately, but a rewrite request including information on the track to be rewritten and the shift amount of the off track is held. And the rewrite request being held is executed at a timing which is different from the write retry. So rewrite processing can be executed after vibration, which caused the off track, stops, and the generation of an off track error during rewrite processing and the generation of further off track writing can be prevented.