Sync-mark detection error recovery in hard disc drives
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Solution Overview
Problem
Existing sync-mark detection recovery techniques in hard disc drives (HDDs) are slow and cumbersome, often requiring extensive firmware intervention and leading to lengthy recovery times, especially in scenarios with media defects or offset read operations.
Innovation Solution
A data recovery method that divides sectors into data fragments with associated sync-marks, reads and re-reads these fragments, and updates sample data fragments in memory to improve sync-mark detection reliability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing sync-mark detection recovery techniques are used, then sync-mark detection failures can be recovered from, but recovery times become lengthy and command completion time deteriorates
Solution Approach 1:
The patent divides a sector into multiple data fragments, each with its own sync-mark detection. This segmentation allows the system to process and recover individual fragments independently rather than requiring recovery of the entire sector, significantly reducing recovery time while maintaining data integrity
Solution Approach 2:
The patent performs preliminary actions by pre-processing and storing syndrome information for each data fragment before actual read operations. When sync-mark detection fails, this pre-computed information enables rapid recovery without requiring time-consuming re-reading of entire sectors
2Reliability
If existing sync-mark detection recovery techniques are used, then detection failures can be handled, but firmware intervention complexity increases
Solution Approach 1:
The patent implements self-service mechanisms where the hardware automatically performs syndrome computation, data fragment reassembly, and error correction without requiring firmware intervention. The controller autonomously manages the recovery process by utilizing pre-stored syndrome information and systematically re-reading only the necessary data fragments
Solution Approach 2:
The patent introduces syndrome information as an intermediary element that mediates between the raw data fragments and the final decoded output. This intermediary contains pre-computed error detection and correction information that simplifies the recovery process by providing a direct path to reconstruct corrupted data without complex firmware algorithms
3Productivity
If sectors are divided into data fragments with individual sync-marks, then recovery efficiency improves, but device complexity increases
Solution Approach 1:
The patent merges the syndrome computation function into the hardware controller, combining error detection and correction capabilities directly into the data fragment processing pipeline. This integration allows simultaneous processing of multiple data fragments with unified syndrome information, improving recovery efficiency while managing complexity through consolidation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach efficiently manages sync-mark detection failures, reducing recovery times and improving command completion time performance in HDDs by enhancing sync-mark detection reliability and sample quality through recursive read averaging and error recovery mechanisms.
Implementation Method 1
Data stored on a hard-disk drive (HDD) is retrieved by demodulating a signal induced by passing a magneto-resistive read-head over its location on a magnetic media
Data Source
AI summary
Sync-mark (SM) detection recovery techniques for HDDs tend to be slow and cumbersome. Typical approaches often require an entire read command to be aborted and multiple subsequent read commands with significant firmware intervention. Should a data sector be unreadable, an example recovery technique for HDDs is recursive read averaging (RRA). Using RRA, samples for failed sector reads are stored in memory. When a sector is subsequently read, the samples are averaged and replace the prior sample stored in memory. The averaged samples are then used to decode the sector. Should SMs associated with data fragments making up a sector be unreadable, the data fragments are unreadable, rendering the sector unreadable. The systems and methods described herein are used to recover previously unreadable SMs. When updated data fragments are subsequently recombined, the confidence level in the overall sector is improved, which increases the likelihood of a successful decode of the sector.