Read Element Radial Offset Adjustment for Encroached Track Recovery
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Solution Overview
Problem
Data storage devices, such as hard disc drives, face challenges in recovering user data due to mechanical shocks or vibrations causing adjacent track encroachment, where data from one track overlaps with an adjacent track, leading to uncorrectable read errors, especially with smaller track widths and shingled magnetic recording, which traditional read retry operations may fail to address effectively.
Innovation Solution
A method involving a moveable read element that radially advances from a first offset to a second offset during a read retry operation across a data sector, with optimal offsets determined for each segment to ensure complete data recovery, using a trajectory profile that adjusts based on error detection patterns to maintain signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional read retry operations are used with fixed offset values, then the operation is simple and fast, but data recovery fails when adjacent track encroachment occurs
Solution Approach 1:
The patent applies dynamics by transitioning from fixed offset values to dynamic, variable offset values during read retry operations. The read element's radial position is continuously adjusted based on the detected encroachment pattern, allowing the system to adapt to variable encroachment conditions across different segments of a data sector. This dynamic adjustment enables successful data recovery from tracks with adjacent track encroachment that cannot be handled by traditional fixed-offset methods.
Solution Approach 2:
The patent changes the offset parameter from a fixed value to a variable value that changes across different segments of a data sector. By determining optimal offset values for each segment based on encroachment detection, the system can compensate for adjacent track interference. This parameter change approach allows the read element to maintain optimal positioning relative to the intended track despite encroachment from adjacent tracks.
2Quantity of substance
If smaller track widths are used to increase storage density, then storage capacity increases, but track alignment becomes more sensitive to mechanical disturbances
Solution Approach 1:
The patent applies local quality by segmenting the data sector into multiple segments and determining optimal offset values for each segment independently. This allows the system to address local variations in encroachment patterns that occur across different portions of a track. By treating each segment with customized offset adjustments, the system can maintain reliable track alignment even with smaller, more densely packed tracks that are more susceptible to mechanical disturbances.
Solution Approach 2:
The patent segments the data sector into multiple segments to independently analyze and compensate for encroachment in each segment. This segmentation allows the system to identify and correct localized alignment issues caused by mechanical shocks or vibrations. By processing each segment separately with its own optimal offset value, the system maintains reliable data recovery from densely packed tracks that would otherwise be vulnerable to alignment errors.
3Quantity of substance
If shingled magnetic recording is used to increase density, then storage capacity increases, but read errors increase due to variable encroachment patterns
Solution Approach 1:
The patent uses dynamics to adapt to the variable encroachment patterns inherent in shingled magnetic recording. By continuously adjusting the offset value for each segment based on detected encroachment, the system can dynamically compensate for the overlapping track interference that characterizes shingled recording. This dynamic approach makes it possible to detect and correct read errors that would otherwise be undetectable or uncorrectable in densely packed shingled tracks.
Solution Approach 2:
The patent implements feedback by detecting encroachment patterns in each segment and using that information to determine optimal offset values for subsequent reading operations. This feedback loop allows the system to identify and correct read errors caused by shingled recording interference. By continuously monitoring and adjusting offset based on detected conditions, the system overcomes the increased read error difficulty associated with high-density shingled magnetic recording.
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 effectively recovers data from sectors with variable encroachment by ensuring continuous radial translation of the read element, improving data retrieval reliability and signal quality across the entire sector, even in cases of severe mechanical disturbances.
Implementation Method 1
a moveable read element detects at least one uncorrectable read error in user data stored in a data sector arranged along a concentric track
Data Source
AI summary
Method and apparatus for recovering user data from a rotatable data recording medium. In some embodiments, a moveable read element detects at least one uncorrectable read error in user data stored in a data sector arranged along a concentric track. A read retry operation is carried out to recover the user data by radially advancing the moveable read element from a first offset value to a different second offset value with respect to the track in accordance with a trajectory profile while transducing the user data from the data sector. This allows data that are variably overwritten (encroached upon) by different radial amounts from an adjacent track to be recovered.