Magnetic Disk Device Shingled Recording Data Loss Prevention
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Solution Overview
Problem
Magnetic disk devices face challenges in efficiently managing data storage and retrieval due to the limitations of shingled recording techniques, which result in data loss during power shutdowns and inefficiencies in data access and throughput.
Innovation Solution
A magnetic disk device configuration that includes a media cache and a system controller to reserve and manage data regions, allowing for sequential writing and bypass writing, and utilizing a spare band to switch data, thereby preventing data loss and improving access efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If shingled recording is used to achieve high recording density, then recording capacity is improved, but data loss occurs during power shutdowns
Solution Approach 1:
The patent applies preliminary action by reserving a spare band region before power shutdown occurs. The controller identifies and designates a spare band in advance, ensuring that data can be safely written to this reserved region before the shutdown event, thereby preventing data loss while maintaining high recording density through shingled recording
Solution Approach 2:
The spare band acts as an intermediary region between the active data bands and the media cache. During power shutdown scenarios, this intermediary spare band receives data that would otherwise be lost, serving as a buffer that protects against information loss while the shingled recording maintains high capacity
2Quantity of substance
If shingled recording is used to increase recording density, then storage capacity is improved, but data access efficiency deteriorates
Solution Approach 1:
The patent segments the disk structure into distinct regions: active data bands, media cache, and spare band. This segmentation allows the controller to manage data access efficiently by directing operations to appropriate regions, mitigating the access efficiency deterioration that would otherwise result from shingled recording's overlapping track structure
Solution Approach 2:
The media cache serves as an intermediary layer between the host system and the shingled recording regions. It buffers data transfers, allowing high-speed data access without requiring direct access to the physically constrained shingled tracks, thereby maintaining fast access speeds while preserving high storage capacity
3Productivity
If media cache is used to improve data access efficiency, then write throughput is improved, but device complexity increases
Solution Approach 1:
The controller performs preliminary actions by pre-allocating and managing the media cache and spare band regions before data write operations begin. This preliminary setup enables efficient write throughput during operation without requiring complex real-time decision-making, thereby improving productivity while keeping device complexity manageable
Solution Approach 2:
The media cache and spare band management system operates with a degree of autonomy, automatically identifying spare bands, managing cache contents, and coordinating write operations without requiring complex external control. This self-service capability improves write throughput while minimizing the complexity burden on the overall device architecture
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
Enhances data storage efficiency by preventing data loss during power shutdowns and improving write processing performance by efficiently managing data regions and access within the media cache.
Implementation Method 1
a magnetic disk device includes a disk, a head, and a controller... write the first data to a fourth region, write the second data after the first data in the fourth region
Data Source
AI summary
According to one embodiment, a magnetic disk device includes a disk having a first region to which data is written by normal recording and a second region to which data is written by shingled recording, a head configured to write the data to the disk and read the data from the disk, and a controller configured to, when first data and second data is to be sequentially written to a third region of the second region, reserve a fourth region corresponding to the first data and the second data in the first region, write the first data to the fourth region, write the second data after the first data in the fourth region, and sequentially write the first data and the second data read from the fourth region to the third region.