Magnetic Disk Device Shingled Recording Data Integrity
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Solution Overview
Problem
Conventional magnetic recording technologies face challenges in efficiently writing and reading data across multiple tracks on a magnetic disk, particularly in shingled magnetic recording modes, where data is written in overlapping segments, leading to issues with data integrity and recording density.
Innovation Solution
The magnetic disk device employs a hybrid recording approach that includes a write processing unit capable of executing sequential write operations across multiple data tracks. This unit writes data to specific segments of different data sectors in a manner that optimizes data placement and reduces the adverse effects of data overlap, such as squeeze errors, by distributing the impact across multiple segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If shingled magnetic recording is used to increase recording density, then recording density is improved, but data integrity deteriorates due to squeeze errors from overlapping tracks
Solution Approach 1:
The patent divides a data sector into multiple segments (e.g., 4 segments per sector) and distributes them across different tracks. This segmentation allows the system to handle squeeze errors on a per-segment basis rather than per-sector, improving data integrity while maintaining high recording density through shingled magnetic recording.
Solution Approach 2:
The patent performs preliminary identification of squeeze-prone segments during the write operation. By identifying which segments are likely to be affected by track squeeze before finalizing the write, the system can take preventive measures or prepare for error correction, thereby maintaining data integrity in high-density shingled recording.
2Reliability
If sequential write operations are performed across multiple tracks to distribute data segments, then data integrity is improved, but write time increases
Solution Approach 1:
The patent maintains continuous write operations across multiple tracks by buffering segment data and sequentially writing to different tracks without stopping the overall write process. This continuity minimizes the impact on write time while still distributing data segments to improve data integrity.
Solution Approach 2:
The patent performs preliminary buffering of segment data in memory before the actual write operation. This allows the system to prepare all segment data in advance and execute the multi-track write operation efficiently, reducing the overall write time penalty associated with distributed writing.
3Productivity
If multiple read heads are used to simultaneously read from multiple tracks, then read efficiency is improved, but device complexity increases
Solution Approach 1:
The patent designs the read head assembly to serve multiple functions: the same read heads that read from individual tracks can also read from multiple tracks simultaneously when positioned appropriately. This multi-functionality improves read efficiency without requiring separate dedicated read heads for each track, thereby limiting the increase in device complexity.
4Quantity of substance
If data sectors are divided into multiple segments across tracks, then recording density is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent segments data sectors and distributes them across multiple tracks, which inherently requires precise track positioning and alignment. This segmentation strategy achieves high recording density but simultaneously increases manufacturing precision requirements for track formation and head positioning.
Solution Approach 2:
The patent employs feedback mechanisms through servo patterns and track identification procedures that allow the system to detect and compensate for positioning errors during operation. This feedback reduces the impact of manufacturing precision limitations, enabling high-density segment distribution across tracks even with moderate manufacturing tolerances.
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 the efficiency of data write and read processes, improves data integrity by reducing errors associated with data overlap, and increases recording density by effectively managing data segments across multiple tracks.
Implementation Method 1
a write head that writes data to a recording layer of the disk
Implementation Method 2
a first read head, a second read head, and a third read head that each read data from a recording layer of the disk
Data Source
AI summary
According to one embodiment, a magnetic disk device includes a disk, a write head, and a write processing unit. The write processing unit executes first write processing of writing data to a first segment of a first data sector in a first data track. The write processing unit then executes second write processing of writing data to a first segment of a second data sector in the first data track. The write processing unit then executes third write processing of writing data to a second segment of the first data sector in a second data track.