Multi-head Disk Drive Sorted Data Zones for Rate Stability
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Solution Overview
Problem
Multi-head disk drives experience undesirable large fluctuations in sequential data rate due to format variations among disk surfaces caused by differences in head performance, leading to inefficient data transfer.
Innovation Solution
The controller orders head-zone combinations from highest to lowest data rate and writes data sequentially through this ordered list, ensuring that lower performing heads are used only when the data rate decreases to their associated rate, thereby smoothing the data rate curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data is written to multiple disk surfaces with format variations, then storage capacity is increased, but sequential data rate fluctuations increase
Solution Approach 1:
The patent segments the writing process by dividing data into portions and assigning each portion to specific head-zone combinations based on performance characteristics. The controller segments the multi-head system into performance-based groups, writing data to higher performing heads first, then to lower performing heads, thereby maintaining stable sequential data rates while utilizing all available storage capacity across multiple disk surfaces
Solution Approach 2:
The patent applies local quality by treating different heads and zones with differentiated writing strategies based on their specific performance characteristics. The controller identifies and prioritizes higher performing head-zone combinations for data writing, while lower performing combinations are used subsequently. This localized optimization ensures that each portion of data is written to the most appropriate medium, stabilizing overall sequential data rates while maximizing storage utilization
2Stability of the object's composition
If higher performing heads are used preferentially, then sequential data rate stability is improved, but device complexity increases
Solution Approach 1:
The controller performs preliminary actions by pre-characterizing and sorting all head-zone combinations according to their data rate performance before the actual data writing begins. This preliminary sorting creates a performance-based writing sequence that simplifies the control logic during operation, as the controller only needs to follow the pre-established sequence rather than making complex real-time decisions, thereby achieving data rate stability with manageable complexity
Data Source
AI summary
A multi-head disk drive is disclosed comprising a plurality of disk surfaces, and a head assembly comprising a plurality of heads, wherein each disk surface comprises a plurality of data zones, and each data zone having a data transfer rate different from the other zones of the respective disk surface. A controller is operable to sequentially write a sequence of data blocks to the plurality of disk surfaces in accordance with a list of head-zone combinations, each head-zone combination corresponding to one of the heads and one of the data zones of the respective disk surface. The head-zone combinations in the list are ordered from highest data transfer rate to lowest data transfer rate, and each disk surface comprises a pivot point defining a direction of writing data in the data zones from one of an outer diameter toward a middle diameter and an inner diameter toward the middle diameter.