Flexible Logical Tracks for Radius-Independent Data Rate
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Solution Overview
Problem
Conventional disk drives experience a decrease in sectors per track as the track diameter decreases, leading to a proportional decrease in I/O data rate, resulting in unused I/O channel bandwidth.
Innovation Solution
The implementation of flexible logical tracks (FLT) that abstract logical tracks from physical tracks, allowing them to extend over extra fractions of physical tracks, including donor tracks on opposing disk surfaces, to maintain a constant number of sectors per revolution and per logical track.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional physical tracks are used with fixed radial density, then the disk drive can maintain simple track formatting, but the I/O data rate decreases proportionally with track diameter, resulting in unused I/O channel bandwidth
Solution Approach 1:
The patent divides the disk surface into multiple zones with different radial densities, allowing each zone to have optimized track formatting. This segmentation enables the I/O channel to operate at full bandwidth in outer zones while inner zones use fewer sectors, resolving the contradiction between maintaining simple formatting and achieving high data rates.
Solution Approach 2:
The patent introduces a logical track layer that maps to multiple physical tracks across different radii. This dimensional transformation allows data to be organized in logical sectors that can span multiple physical zones, enabling constant data rate operation regardless of track diameter while maintaining flexible physical formatting.
2Productivity
If the number of sectors per track is increased to maintain constant data rate, then the I/O channel bandwidth is fully utilized, but additional back-end channel decoders are required
Solution Approach 1:
The patent creates a universal logical sector structure that can accommodate variable physical sector counts across different track radii. This multi-functional logical layer allows the same I/O channel and decoder infrastructure to handle both high-density outer tracks and low-density inner tracks without requiring additional decoders, resolving the contradiction between high data rate and decoder complexity.
3Ease of manufacture
If radial density is kept constant across all tracks, then manufacturing is simplified, but inner tracks have fewer sectors and lower data rates, leaving I/O channel capacity unused
Solution Approach 1:
The patent implements dynamic sector allocation where the number of sectors per track varies by radial zone. This dynamic formatting allows outer tracks to use higher sector counts for maximum data rate while inner tracks use fewer sectors appropriate to their circumference, fully utilizing I/O channel bandwidth across all zones while maintaining manufacturable track density gradients.
Data Source
AI summary
Various illustrative aspects are directed to a data storage device, comprising one or more disks; at least one actuator mechanism configured to position at least a first head proximate to a first disk surface and a second head proximate to a second disk surface; and one or more processing devices. The one or more processing devices are configured to: assign logical tracks to physical tracks of the disk surfaces such that a respective logical track comprises: at least a portion of sectors of a primary physical track, the primary physical track being on the first disk surface; and at least a portion of sectors of a donor physical track, the donor physical track being on the second disk surface. The one or more processing devices are configured to perform, using the first head and the second head, a data access operation with at least one of the logical tracks.