Zone-Based Band Mapping for Shingled Magnetic Recording Data Integrity
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Solution Overview
Problem
Shingled magnetic recording (SMR) systems face challenges in data integrity and performance due to the single-write direction constraint, which can result in data loss during power failures and inefficient write operations, especially when rewriting tracks requires rewriting multiple shingled tracks.
Innovation Solution
Implementing zone-based band mapping with dynamic band remapping and a read-modify-write-write (RMWW) operation to write data to a spare 'empty' band, ensuring data integrity by maintaining a copy of original data and using a unique seed for each write operation to track progress, and optionally employing a scratch pad for additional safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If shingled magnetic recording is used to increase storage density, then storage capacity is improved, but data integrity deteriorates due to single-write direction constraint and power failure vulnerability
Solution Approach 1:
The patent segments the storage medium into multiple bands of tracks, where each band can be independently managed. This segmentation allows the system to perform read-modify-write operations on individual bands without affecting other bands, thereby maintaining data integrity while enabling efficient write operations in shingled magnetic recording systems.
Solution Approach 2:
The patent implements preliminary actions by reading existing data from the target band before writing new data. This read-modify-write approach ensures that data integrity is maintained by preserving valid data portions that are not being overwritten, while still allowing the system to achieve high storage density through shingled recording.
2Ease of operation
If rewriting tracks in shingled magnetic recording is performed, then data updates are achieved, but write operation efficiency deteriorates due to requirement to rewrite multiple shingled tracks
Solution Approach 1:
By organizing tracks into separate bands, the patent enables selective writing to individual bands. When a data update is needed, the system only needs to perform read-modify-write operations on the specific band containing the target track, rather than rewriting multiple shingled tracks across different bands. This significantly improves write operation efficiency while maintaining data update capability.
Solution Approach 2:
The patent introduces a band mapping structure that acts as an intermediary between the logical track addresses and physical track locations. This mapping allows the system to efficiently locate and update only the necessary bands, reducing the overhead of rewriting multiple tracks and improving overall write operation efficiency.
3Reliability
If read-modify-write operations are performed on shingled tracks, then data integrity is improved, but operation time increases due to additional read and write steps
Solution Approach 1:
The patent segments the storage medium into multiple bands, allowing read-modify-write operations to be confined to individual bands. This segmentation reduces the total operation time by limiting the scope of reads and writes to only the necessary band, rather than requiring operations across multiple shingled tracks. Data integrity is maintained through the read-modify-write process while operation time is reduced through band-level isolation.
Solution Approach 2:
The patent applies local quality by performing read-modify-write operations only on the specific band containing the target data, rather than uniformly processing all tracks. This localized approach maintains data integrity where needed while minimizing unnecessary read and write operations in other bands, thereby reducing overall operation time.
Data Source
AI summary
Systems and methods for zone-based band mapping in a data storage device are disclosed. In one embodiment, a device may comprise a first data storage medium including a first band of tracks and a second band of tracks, each band of tracks including multiple adjacent tracks that are at least partially overlapped. The device may further comprise a processor configured to receive a write command to store received data to the first band of tracks, read previously stored data from the first band of tracks, modify the previously stored data with the received data to generate first modified data, write the first modified data to the second band of tracks, and assign a first data storage location indicator previously associated with the first band of tracks to the second band of tracks.