Magnetic Disk Sector Mapping for SMR Recording Quality
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Solution Overview
Problem
Magnetic disk apparatuses using shingled magnetic recording (SMR) face challenges with recording quality due to narrow track pitches, leading to susceptibility to adjacent track erasure and uneven recording quality across sectors.
Innovation Solution
A method that involves quality inspection of sectors on a magnetic disk, calculation of surplus sectors based on actual and set capacities, selection of sectors with low recording quality, and reassignment of logical block addresses (LBAs) to sectors with higher recording quality, particularly those in the end track with better recording performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If shingled magnetic recording (SMR) is used to improve recording density, then track pitch can be made narrower, but recording quality deteriorates due to adjacent track erasure
Solution Approach 1:
The patent applies local quality by identifying and categorizing different sectors on the magnetic disk based on their recording quality characteristics. Specifically, it divides sectors into first sectors (with first recording quality) and second sectors (with second recording quality), and assigns different logical block addresses to each category. This allows the system to optimize for both high-density SMR recording and reliable data storage by directing data to appropriate quality zones.
Solution Approach 2:
The patent changes the parameter of track pitch to achieve higher recording density through SMR, while compensating for the resulting recording quality deterioration through software-based sector classification and LBA reassignment. The system dynamically adjusts the mapping between logical block addresses and physical sectors based on recorded quality metrics.
2Quantity of substance
If shingled magnetic recording (SMR) is used to improve recording density, then track pitch can be made narrower, but susceptibility to adjacent track erasure increases
Solution Approach 1:
The patent identifies sectors that are more susceptible to adjacent track erasure due to narrower track pitches in SMR, and creates a separate classification for these affected sectors. By assigning different LBAs to sectors based on their susceptibility levels, the system can protect critical data from being written to vulnerable sectors while maintaining high overall recording density.
3Device complexity
If sectors with different recording quality are uniformly addressed, then address assignment is simplified, but data storage reliability decreases
Solution Approach 1:
The patent resolves this contradiction by implementing non-uniform LBA assignment based on local sector quality characteristics. Sectors are divided into at least two categories based on recording quality metrics, and each category receives distinct LBA ranges. This approach increases address assignment complexity slightly but dramatically improves data storage reliability by ensuring critical data is stored in higher-quality sectors.
Solution Approach 2:
The patent performs preliminary quality assessment and sector classification during the manufacturing or initialization phase. Quality inspection results are recorded and used to pre-assign LBAs to sectors based on their quality characteristics. This preliminary action eliminates the need for complex real-time quality assessment during data operations, balancing reliability with operational simplicity.
Data Source
AI summary
A method according to one embodiment includes acquiring a result of quality inspection related to recording quality of first sectors included in a first storage area of a magnetic disk. The method includes calculating a first number being the number of sectors corresponding to a capacity obtained by subtracting a set capacity from an actual capacity of the first storage area. The first number is calculated based on the set capacity of the first storage area and a set value of recording density of the first storage area. The method includes selecting a second number of sectors from the first sectors based on the result of quality inspection. The method includes assigning addresses to a group of sectors that are not included in the second number of sectors among the first sectors. The group of sectors consists of sectors with the number corresponding to the set capacity.