HDD Sector Interleaving Layout for ECC Reliability and Low Latency
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Solution Overview
Problem
Existing data storage technologies face challenges in efficiently writing and reading data on hard disc drives (HDDs) due to issues like sector failure, skew problems, and performance penalties, particularly when dealing with local impairments and vibrations, which affect signal-to-noise ratio and require complex operations like read-modify-write or dual channels.
Innovation Solution
The method involves encoding data sectors with a single error correcting code (ECC) and dividing them into multiple portions, which are then interleaved with spaces on a track, allowing for uniform latency and space diversity to mitigate these issues without requiring read-modify-write operations or additional channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is written using traditional sector-based encoding on HDDs, then data storage is straightforward, but local impairments and vibrations cause sector failure and require complex read-modify-write operations
Solution Approach 1:
The patent divides each data sector into multiple sub-sectors (e.g., 4 sub-sectors per sector) and distributes them across different physical locations on the disk track. This segmentation allows the system to avoid read-modify-write operations by reading only the specific sub-sector that needs updating, thereby reducing operation complexity while maintaining data reliability through spatial distribution that mitigates local impairments and vibrations
2Reliability
If data sectors are distributed across multiple tracks to mitigate local impairments, then data reliability improves, but skew problems and performance penalties occur
Solution Approach 1:
The patent transitions from distributing data across multiple tracks (horizontal distribution) to distributing sub-sectors within a single track by exploiting the radial dimension of the disk. By placing sub-sectors at different radial positions along the same track, the system achieves spatial diversity to mitigate local impairments while avoiding skew problems and performance penalties associated with multi-track operations
3Reliability
If traditional interleaving is used to distribute data, then error correction is improved, but read latency varies and performance is degraded
Solution Approach 1:
The patent applies local quality by assigning different interleaving patterns to different sub-sectors within the same sector based on their specific physical locations and error susceptibility. Rather than using a uniform interleaving pattern across all data, the system optimizes each sub-sector's pattern locally, improving error correction capability while minimizing variations in read latency and maintaining overall performance
Data Source
AI summary
A method includes encoding a sector of data to be written to a data storage device with a single error correcting code (ECC). The sector of data is divided into N individually readable and writeable portions, with N≥2. The individually readable and writeable portions of the sector of data are separated with a space between the portions of the sector of data in a pattern.