Shingled Storage Track Width Variability Compensation
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Solution Overview
Problem
Shingled recording techniques lead to variability in storage media data track widths, causing signal-to-noise ratio (SNR) variability and increasing the unrecoverable error rate (UER) due to narrow effective written widths resulting from overlapping tracks.
Innovation Solution
A control unit in storage devices determines the effective width of a first track by analyzing the overlap with a second track and performs additional write operations, such as rewriting data to a third track or adding redundancy information, if the effective width falls below a threshold, to mitigate SNR degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If shingled recording techniques are used to increase storage capacity, then storage density is improved, but track width variability increases causing SNR degradation and increased UER
Solution Approach 1:
The system performs preliminary detection of track width before data writing, and pre-prepares compensation measures by identifying tracks that require additional redundancy information or rewriting operations in advance, preventing SNR degradation before it occurs
Solution Approach 2:
The system dynamically adjusts writing parameters including redundancy information addition and track rewriting based on detected track width measurements, changing operational parameters to compensate for narrow effective widths and maintain reliable data storage
2Quantity of substance
If overlapping tracks are written to increase storage density, then storage capacity is improved, but effective track width decreases causing SNR variability
Solution Approach 1:
The system implements a feedback mechanism where track width is measured after writing, and this measurement feeds back to determine whether compensation operations (rewriting or redundancy addition) are needed, creating a closed-loop control system that maintains track width consistency
Solution Approach 2:
The system addresses the two-dimensional track width problem by adding a third dimension of redundancy information, using additional data layers or error correction codes to compensate for narrow effective widths without changing the physical track layout
3Reliability
If additional write operations are performed to compensate for narrow tracks, then data reliability is improved, but writing time increases
Solution Approach 1:
The system applies partial compensation by adding redundancy information only to tracks that fall within specific width thresholds, rather than rewriting all tracks, achieving sufficient reliability improvement with minimal additional time investment
Solution Approach 2:
The system performs track width detection and compensation decisions during the initial writing process rather than after, integrating compensation operations into the original write sequence to minimize total writing time
Data Source
AI summary
Various approaches that reduce the width variability of storage media data tracks are described. First and second data tracks are written so that the second track overlaps the first track. After writing the second track data to the second track, an effective width of the first track is determined. The effective width of the first track is the portion of the first track that is not overlapped by the second track. One or more additional write operations to the recording medium are performed to compensate for the effective width of the first track being less than a threshold. The additional write operations may include one or more of rewriting the first track data to a third track on the storage medium and writing additional redundancy information to supplement the coding of the first track data.