Hard Disk Track Segmentation for Variable Recording Density
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Solution Overview
Problem
Current methods for selecting recording density in hard-disk drives assume uniform magnetic-recording disk characteristics, leading to excessive density in weaker regions and increased error rates, while existing approaches either reduce overall capacity or are impractical due to large defect lists.
Innovation Solution
Divide a track into multiple portions and adjust the recording density independently for each portion based on its relative strength, allowing different write frequencies to balance error rates across the track without compromising overall capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform recording density is selected for all tracks, then manufacturing process is simple, but error rate increases in weaker regions of the track
Solution Approach 1:
The track is divided into multiple portions (e.g., first portion, second portion, third portion) along its circumferential path. Each portion is then written with independently optimized recording density parameters, allowing weaker regions to use lower densities while stronger regions use higher densities, thus resolving the contradiction between simple uniform recording and reliable error-free reading.
Solution Approach 2:
Different portions of the track are assigned different recording density characteristics based on their local magnetic properties. The system identifies weaker portions (with higher error rates) and stronger portions (with lower error rates) and optimizes the write frequency and density for each local region, achieving overall reliability without sacrificing capacity in strong regions.
2Quantity of substance
If recording density is increased to maximize data storage, then capacity increases, but error rate increases in weaker track regions
Solution Approach 1:
The track is segmented into multiple portions that can be independently optimized. This allows the system to write at high density in stronger portions while using lower density in weaker portions, maximizing overall capacity without allowing errors to propagate across the entire track.
Solution Approach 2:
The system dynamically changes recording parameters (write frequency, density) based on the local characteristics of each track portion. By detecting which portions are weaker and adjusting parameters accordingly, the system maintains high capacity in strong regions while ensuring reliability in weak regions.
3Reliability
If zone bit recording is used to adjust density across zones, then recording density is optimized, but device complexity increases
Solution Approach 1:
Instead of using complex zone-based control, the system segments the track into portions and uses simpler, more direct control mechanisms to adjust density locally. This reduces the complexity of the control system while achieving similar or better density optimization by focusing on specific track portions rather than entire zones.
Solution Approach 2:
The system dynamically adjusts recording parameters on a per-portion basis during the writing process, allowing flexible optimization without requiring complex pre-planned zone structures. This dynamic approach simplifies the overall device architecture while maintaining high reliability.
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 maintains desired average error rates without reducing net capacity, providing an extra soft error rate margin and accommodating varying disk imperfections, thus enhancing data storage reliability and efficiency.
Implementation Method 1
A read/write head uses a magnetic field to read data from and write data to the surface of a magnetic-recording disk
Implementation Method 2
an actuator relies on air pressure inside the hard drive enclosure to support the read/write heads at the proper distance away from the surface of the magnetic-recording disk
Implementation Method 3
the air pulled along by a spinning magnetic-recording disk forces the head away from the surface of the magnetic-recording disk
Data Source
AI summary
Approaches for adjusting the recording density of a recording medium in a circumferential direction are disclosed. A hard-disk drive includes one or more electronic components configured to divide a track, of a plurality of concentric tracks on a magnetic-recording disk, into a plurality of portions, and write data to each of the plurality of portions at a recording density that is independent of the recording density used for any of the other portions. Data may be written to a first portion of a track at a different frequency than to a second portion of the same track. The frequency at which data is written may be adjusted for different portions of the same track to allow the frequency to be reduced at certain portions shown to have relatively higher soft error rate while increasing the frequency for other portions to achieve a desired average error rate for the track.