Track Squeeze Metric Abort for Data Storage Integrity
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Solution Overview
Problem
Existing data storage devices face challenges in maintaining accurate head positioning during write operations, leading to potential data corruption in adjacent tracks due to off-track writes, which can result in unrecoverable data sectors and require complex redundancy mechanisms to ensure data integrity.
Innovation Solution
A track squeeze metric is generated and accumulated based on position error signals during write operations, with the write being aborted when the metric exceeds a threshold, and track level redundancy is used to correct errors, ensuring data integrity by dynamically adjusting thresholds and using parity sectors for error correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the head is positioned closer to the disk surface to increase storage density, then storage capacity is improved, but the risk of off-track writes and data corruption in adjacent tracks increases
Solution Approach 1:
The system performs preliminary monitoring of head position and track squeeze metrics before completing write operations. By accumulating track squeeze metrics during the write process and comparing against thresholds, the system detects potential off-track conditions early and aborts writes before data corruption occurs, preventing the harmful effect while maintaining high storage density
Solution Approach 2:
The system continuously monitors head position through position error signals (PES) and servo data, feeding this information back to control the write operation. The track squeeze metric accumulation provides feedback on the cumulative effect of head positioning deviations, enabling dynamic adjustment of write operations to prevent adjacent track corruption while maintaining high areal density
2Reliability
If track level redundancy is increased to correct errors in adjacent tracks, then data integrity is improved, but device complexity and storage capacity are reduced
Solution Approach 1:
The system dynamically changes operational parameters by adjusting write abort thresholds based on accumulated track squeeze metrics. Instead of using fixed redundancy mechanisms, the system adapts the write operation parameters (thresholds for aborting writes) based on real-time head position feedback, reducing the need for complex static redundancy while maintaining data integrity
Solution Approach 2:
The system applies partial redundancy through track level coding only when necessary, rather than using full redundancy across all data. By monitoring track squeeze metrics and aborting writes only when corruption is likely, the system applies error protection selectively, reducing overall system complexity while maintaining adequate data integrity
3Object-affected harmful factors
If write operations are monitored more closely to prevent off-track writes, then data corruption is reduced, but write speed and productivity are decreased
Solution Approach 1:
The system uses accumulated track squeeze metrics to quickly assess whether a write operation is at risk of corruption. When the metric remains below thresholds, the system allows writes to proceed without intensive monitoring, effectively skipping detailed checks during safe operations and maintaining high write speed while still preventing corruption when risks are detected
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 minimizes data corruption by aborting writes when track squeeze metrics exceed thresholds, preserving the correction power of track level redundancy and ensuring reliable data recovery, thus enhancing data storage capacity and integrity.
Implementation Method 1
a head connected to a distal end of an actuator arm which is rotated about a pivot by a voice coil motor (VCM) to position the head radially over the disk
Implementation Method 2
The servo sectors comprise head positioning information (e.g., a track address) which is read by the head and processed by a servo control system to control the actuator arm as it seeks from track to track
Data Source
AI summary
A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of data tracks, including consecutive data tracks N−1 and N. A first write to data track N is performed using a first position error signal (PES) representing a position of the head relative to the data tracks. A track squeeze metric is generated for data track N−1 based on at least the first PES of the first write. The track squeeze metric for data track N−1 is accumulated during the first write, and the first write is aborted when the accumulated track squeeze metric for data track N−1 exceeds a first threshold.