HAMR Head Sorting by Reader Writer Widths
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Solution Overview
Problem
Heat-assisted magnetic recording (HAMR) devices face reliability challenges due to varying write power on hours (WPOH) across different capacity drives, with smaller capacity drives experiencing higher WPOH per head and larger capacity drives experiencing lower WPOH per head, leading to inconsistent head life and reliability.
Innovation Solution
The solution involves measuring and sorting HAMR read/write heads based on their reader and writer widths, with heads having higher predicted life used in drives with fewer heads and those with lower predicted life used in drives with more heads, thereby optimizing head usage and reliability across different capacity drives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HAMR read/write heads are used across different capacity drives without sorting, then manufacturing simplicity is maintained, but head reliability varies inconsistently due to different write power on hours per head
Solution Approach 1:
The patent applies preliminary action by measuring and sorting HAMR heads based on reader and writer widths before drive assembly. This pre-sorting ensures that heads with similar durability characteristics are grouped together and assigned to appropriate drive capacity categories, eliminating reliability variations that would otherwise occur during operation. The sorting is performed in advance using width measurements as a proxy for head life prediction.
2Reliability
If heads are sorted by predicted life based on width measurements, then head reliability is improved across different drive capacities, but manufacturing complexity increases
Solution Approach 1:
The patent changes the parameter used for head classification from operational characteristics to physical dimensions. By measuring reader and writer widths—static geometric parameters—the system predicts head life and determines appropriate drive assignments without requiring complex operational testing. This parameter transformation simplifies the manufacturing process while maintaining reliability improvements.
3Reliability
If heads with higher predicted life are used in drives with fewer heads, then drive reliability is optimized, but head allocation complexity increases
Solution Approach 1:
The patent applies local quality by matching specific head characteristics (predicted life based on width measurements) to specific drive requirements (number of heads per drive). Heads with higher predicted life are locally optimized for use in drives with fewer heads where each head experiences higher write power on hours, while heads with lower predicted life are assigned to drives with more heads. This localized matching optimizes overall system reliability.
Data Source
AI summary
For each head in a collection of heat-assisted magnetic recording read/write heads, a reader width and a writer width is measured. A predicted life is determined for each head based on the respective reader width and writer width. In a first set of drives having relatively fewer heads per drive, a first subset of the heads having a higher value of the predicted life are used. In a second set of drives having relatively more heads per drive, a second subset of the heads having a lower value of the predicted life are used.