Magnetic Disk Post Code Switching for SMR CMR Access
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Solution Overview
Problem
Magnetic disk devices using shingled magnetic recording (SMR) face inferior random access performance due to narrower track pitches, which can lead to data destruction when updating multiple tracks, while conventional magnetic recording (CMR) offers better random access but lower storage capacity.
Innovation Solution
A magnetic disk device with a post code area storing both SMR and CMR post codes allows for switching between recording methods, enabling efficient data access and storage by reading post codes in advance, thus omitting the need for on-the-fly generation and reducing switching time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If shingled magnetic recording (SMR) is used to improve storage capacity, then recording density increases, but random access performance deteriorates
Solution Approach 1:
The patent implements dynamic switching between SMR and CMR recording methods based on access patterns. The controller monitors whether accessed tracks belong to SMR or CMR regions and dynamically adjusts the recording method, allowing the system to optimize between storage capacity (SMR) and random access performance (CMR) in real-time based on workload requirements
2Quantity of substance
If track pitch is narrowed to increase recording density, then storage capacity improves, but track update complexity increases due to data destruction risks
Solution Approach 1:
The magnetic disk is divided into distinct SMR regions and CMR regions with clear boundaries. This segmentation allows independent management of each region's characteristics - SMR regions utilize narrow track pitch for high density while CMR regions maintain wider spacing for simpler update operations, eliminating the complexity of managing overlapping tracks across the entire disk
3Adaptability or versatility
If post codes are generated on-the-fly during method switching, then adaptability improves, but switching time increases
Solution Approach 1:
Post codes for both SMR and CMR methods are pre-calculated and stored in the magnetic disk along with the data. When switching between recording methods, the controller can immediately retrieve the appropriate pre-stored post code without performing time-consuming generation operations, significantly reducing method switching time while maintaining full adaptability
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 solution enhances storage capacity and random access performance by allowing seamless method switching without generating post codes, improving format efficiency and reducing switching time between SMR and CMR.
Implementation Method 1
a magnetic head that writes and reads data to and from the magnetic disk
Data Source
AI summary
According to an embodiment, a magnetic disk device includes a magnetic disk including a first storage area and a second storage area different from the first storage area. In the second storage area, both of a first post code that is used to write user data in the first storage area by a first method and a second post code that is used to write user data in the first storage area by a second method are stored in advance. The first method is a method in which one track between two tracks adjacent to each other overlaps a part of the other track between the two tracks. The second method is a method in which two adjacent tracks do not overlap each other.