Variable Track Spacing in Shingled Magnetic Recording
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Solution Overview
Problem
Shingled magnetic recording (SMR) techniques face an increased bit error rate for the first track written in each band due to being partially overwritten by both the second and last tracks in adjacent bands, leading to degraded read performance over time.
Innovation Solution
A write controller adjusts the position of the transducer to make the first and last tracks in a band wider than the remaining tracks, with specific track pitch offset values to ensure adequate spacing and minimize interference, and monitors the readback characteristics to decide when to rewrite the first band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If uniform track pitch is used in SMR, then data storage density is maximized, but the first track in each band experiences increased bit error rate due to being partially overwritten by adjacent tracks
Solution Approach 1:
The patent applies local quality by implementing variable track pitch where the first track in each band has a different (wider) pitch than subsequent tracks. This local modification protects the first track from excessive overwriting while maintaining uniform pitch elsewhere to maximize storage density.
Solution Approach 2:
The patent introduces asymmetry in the track pitch configuration, creating an asymmetric pattern where the first track spacing differs from the spacing between other tracks. This asymmetric design deliberately creates a protective buffer zone for the vulnerable first track while maintaining efficient packing elsewhere.
2Reliability
If variable track pitch is used to protect the first track, then bit error rate decreases, but data storage capacity is reduced
Solution Approach 1:
The patent applies parameter changes by modifying the track pitch parameter specifically for the first track in each band. This selective parameter modification protects the first track from overwriting while minimizing the impact on overall storage capacity by limiting the change to only necessary locations.
3Reliability
If track width is increased for first and last tracks, then readback performance is enhanced, but track spacing requirements increase
Solution Approach 1:
The patent applies local quality by making only the first and last tracks in each band wider than intermediate tracks. This localized width enhancement improves readback performance where it is most needed while maintaining tighter spacing for intermediate tracks to minimize overall pitch requirements.
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 enhances readback performance for the first track in each band, reduces bit error rates, and maintains data integrity by adjusting track widths and pitch offsets, while allowing for efficient data storage capacity.
Implementation Method 1
The transducer is used to write data to the medium in the form of partially overlapping tracks grouped together into bands
Implementation Method 2
The transducer includes a write element and a read element positioned offset from the write element in a radial direction
Data Source
AI summary
Apparatus and method for writing data to a data storage medium using shingled magnetic recording (SMR). In accordance with some embodiments, a transducer is positioned adjacent a recording medium. The transducer is used to write data to the medium in the form of partially overlapping tracks grouped together into bands so that a first track and a last track in a selected band are wider than remaining tracks in the selected band.