Outer Code Redundancy for HDD Flawscan Time Reduction
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Solution Overview
Problem
The manufacturing process of hard-disc drives (HDDs) is time-consuming due to the flawscan operation, which involves writing and reading every sector to locate defects, and existing solutions either compromise reliability or incur significant performance losses when dealing with unscanned tracks.
Innovation Solution
Implementing a multi-sector based error correction technique using outer code error correction, which allows the read portion of the flawscan operation to be performed on a subset of tracks without compromising reliability, and using augmented redundancy systems to ensure data integrity on both scanned and unscanned tracks during manufacturing and in-field usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the read portion of the flawscan operation is performed on a subset of tracks, then manufacturing test-time is reduced, but data integrity may be compromised
Solution Approach 1:
The patent applies preliminary action by generating outer code parity data during the manufacturing process before the drive is deployed. This outer code parity is calculated and stored in advance for tracks that cannot be scanned, enabling error correction to be performed later without requiring time-consuming read operations during manufacturing testing.
Solution Approach 2:
The patent segments the flawscan operation into two parts: tracks that can be scanned during manufacturing and tracks that cannot. For the unscannable tracks, outer code parity is generated and stored separately, allowing the scanning process to focus only on accessible tracks while still ensuring data integrity for all tracks through the combination of scanning results and stored parity data.
2Reliability
If outer code parity is generated for all tracks including unscanned tracks, then data integrity is maintained, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by treating scanned and unscanned tracks differently in the manufacturing process. For scanned tracks, traditional error correction suffices, while for unscanned tracks, outer code parity generation is applied specifically. This localized approach maintains data integrity where needed without unnecessarily complicating the manufacturing process for all tracks.
Solution Approach 2:
The outer code parity data acts as an intermediary that bridges the gap between unscanned tracks and data integrity requirements. Instead of requiring direct scanning of all tracks, the stored outer code parity serves as a mediator that enables error correction for unscanned tracks without adding complex scanning infrastructure or procedures.
3Ease of manufacture
If traditional error correction is used without outer code, then manufacturing process is simpler, but error correction capability is insufficient for unscanned tracks
Solution Approach 1:
The patent generates outer code parity data in advance during manufacturing for tracks that cannot be scanned. This preliminary generation of correction data enables robust error correction capability to be established before deployment, without requiring complex real-time processing or additional scanning infrastructure during manufacturing operations.
Solution Approach 2:
The patent adds another dimension to error correction by introducing outer code parity as a separate layer beyond traditional error correction methods. This additional dimension of redundancy specifically addresses unscanned tracks, enhancing error correction capability without fundamentally altering or complicating the existing manufacturing process for scanned tracks.
Data Source
AI summary
Systems and methods are disclosed for an improved utilization of parity within a data storage device, and manufacturing methods thereof. In some embodiments, a data storage device can implement an improved codeword redundancy process that can be utilized for data storage locations which were not previously scanned for defects. In some embodiments, a data storage device can implement an improved codeword redundancy process to store write data to a data storage location without having to perform a read operation prior to storing the write data to the storage location. The improved codeword redundancy process can include various methods of storing or updating an outer code codeword for the data to be stored.