Multi-Writer HAMR Disk Drive Wear Management
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Solution Overview
Problem
Heat-assisted magnetic recording (HAMR) technology faces challenges in achieving high areal densities due to the wear and tear of near-field transducers (NFTs), which are damaged by the significant energy required for thermal gradients, leading to limited write power on hours (WPOH) and increased failure rates, necessitating the use of high melting point materials that are not optimal for maximum areal densities.
Innovation Solution
Implementing multiple HAMR writers that share the writing load, with one writer taking over when the other reaches a wear threshold, allowing for extended WPOH and improved thermal gradients without the need for high melting point materials, thereby reducing per-surface failure rates and enabling the use of materials that provide better thermal gradients and areal density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single HAMR writer is used to write to the disk surface, then the thermal gradient and areal density can be maximized, but the near-field transducer reaches wear threshold quickly leading to limited WPOH and increased failure rates
Solution Approach 1:
The patent divides the writing function into multiple independent HAMR writers (first writer, second writer) that share the load of writing to the same disk surface at different time periods. This segmentation allows the system to distribute the thermal stress and wear across multiple transducers, extending the overall write power on hours while maintaining the required areal density performance
Solution Approach 2:
The patent implements a wear threshold mechanism where the first HAMR writer is monitored for wear, and when it reaches a predetermined threshold, the system switches to the second HAMR writer. This allows the first writer to be 'discarded' from active service while its functionality is 'recovered' by the second writer, ensuring continuous operation without exceeding wear limits
2Duration of action of moving object
If high melting point materials are used in the near-field transducer to reduce wear, then the WPOH can be extended, but the thermal gradient performance and areal density are compromised
Solution Approach 1:
Instead of modifying the transducer material, the patent segments the writing function across multiple transducers using optimal materials. Each transducer maintains high thermal gradient performance with appropriate materials, while the system achieves extended WPOH through load distribution rather than material compromise
Solution Approach 2:
The patent changes the system parameter from single-transducer longevity to multi-transducer rotation. By changing how the system achieves extended WPOH (from material durability to operational rotation), it preserves the ability to use optimal materials for thermal gradient while still extending overall system lifetime
3Reliability
If multiple HAMR writers are implemented to share the writing load, then the WPOH is extended and failure rates reduced, but the device complexity increases
Solution Approach 1:
The patent merges the functionality of multiple HAMR writers into a unified writing system that operates seamlessly. The first and second writers are combined into a single logical writing unit with automatic switching based on wear thresholds, presenting a unified interface to the disk surface while distributing the physical workload
Solution Approach 2:
The patent implements a feedback mechanism that monitors the wear status of the first HAMR writer and automatically triggers switching to the second writer when thresholds are reached. This feedback loop manages the complexity of multiple writers by providing automated, rule-based switching rather than requiring complex manual management
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 approach significantly reduces the per-surface failure rate and extends the median WPOH requirement, allowing for improved thermal gradients and areal densities, with a 30% advantage over current technologies, while maintaining constant performance throughout the drive's lifetime by switching between writers based on their optimal bit and track densities.
Implementation Method 1
Heat-assisted magnetic recording (HAMR) technology faces challenges in achieving high areal densities due to the wear and tear of near-field transducers (NFTs), which are damaged by the significant energy required for thermal gradients
Implementation Method 2
allowing for extended WPOH and improved thermal gradients without the need for high melting point materials
Data Source
AI summary
A first heat-assisted magnetic recording (HAMR) writer writes to a surface of a magnetic disk using during an initial time period. A second HAMR writer is configured to write to the surface but not during the initial time period. The initial time period extends from a first time when the disk drive is first used to a second time when a near-field transducer of the first HAMR writer reaches a first wear threshold. During a subsequent time period after the initial time period, to the surface of the disk is written to using the second HAMR writer and not the first HAMR writer.