Disk Device Check Value Sector Radial Alignment
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Solution Overview
Problem
In magnetic disk devices, the existing error recovery methods using XOR data lead to increased data corruption due to adjacent track interference (ATI) when rewriting check value sectors, necessitating frequent data recovery processes.
Innovation Solution
The disk device and data management method involve a check value generation circuit that generates XOR data for each track and writes it in a sector adjacent to the user data, aligning XOR sectors radially to prevent ATI from affecting user data, thereby reducing the need for repeated data recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If XOR sectors are written at different circumferential positions (phase shifted) on adjacent tracks to optimize read timing, then read performance is improved, but adjacent track interference increases causing data corruption
Solution Approach 1:
The patent changes the spatial arrangement of XOR sectors from a phase-shifted pattern (optimized for read timing) to a radially aligned pattern (same circumferential position across tracks). This dimensional reorganization eliminates adjacent track interference while maintaining read performance through alternative timing optimization methods.
Solution Approach 2:
The patent converts the harmful effect of radial alignment (which would normally cause ATI) into a benefit by deliberately placing XOR sectors at specific radial positions where they do not interfere with user data sectors, while still achieving optimal read timing through coordinated control of multiple read heads.
2Reliability
If XOR sectors are frequently rewritten to maintain error recovery capability, then error recovery reliability is improved, but data corruption due to adjacent track interference increases
Solution Approach 1:
The patent extracts XOR sectors from the user data area and places them in dedicated check value sectors positioned at specific radial locations. This separation allows frequent rewriting of XOR data without causing adjacent track interference to user data, maintaining error recovery reliability while preventing data corruption.
Solution Approach 2:
The patent introduces dedicated check value sectors as intermediary storage locations for XOR data, positioned between the user data sectors and the interference-prone radial zones. These intermediary sectors act as buffers that absorb the rewriting operations without transmitting interference to user data.
3Productivity
If sector positions are phase shifted on each track to optimize contiguous block reading, then read efficiency is improved, but radial alignment of sector numbers is lost increasing ATI effect
Solution Approach 1:
The patent segments the disk surface into distinct functional zones: user data sectors and dedicated check value sectors. By assigning XOR sectors to specific radial positions in the check value zone, it maintains phase shifting for read efficiency in user data areas while confining ATI effects to the dedicated check value sector zone.
Solution Approach 2:
The patent applies different spatial arrangements to different functional areas: user data sectors maintain phase-shifted positions for optimal read efficiency, while check value sectors are positioned at specific radial locations to minimize ATI. This local differentiation allows each zone to optimize for its specific function without compromising the other.
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 configuration minimizes the impact of ATI on user data, reducing the frequency of data recovery processes and protecting user data from corruption during check value sector updates.
Implementation Method 1
a magnetic recording head to write data to and read data from a plurality of tracks of the disk medium
Implementation Method 2
check value generation circuit configured to generate, for each of the plurality of tracks, check value data based on data stored in one or more sectors of the track
Data Source
AI summary
A disk device includes a disk medium, a magnetic recording head, a processor configured to control the magnetic recording head to write data to and read data from a plurality of tracks of the disk medium on a sector-by-sector basis, and a check value generation circuit configured to generate, for each of the plurality of tracks, check value data based on data stored in one or more sectors of the track. The processor controls the magnetic recording head to write check value data for a first track of the plurality of tracks in a first sector on the disk medium and check value data for a second track of the plurality of tracks in a second sector on the disk medium that is adjacent to the first sector.