Disk Drive Buffer Release Based on Predicted Servo Quality
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing disk drive systems face challenges in maintaining head positioning and fly height stability due to external vibrations and spindle motor degradation, leading to potential data loss and write operation failures during write operations.
Innovation Solution
Implementing a control circuitry that buffers and releases data wedges based on predicted servo metric values for current and future servo sectors, adjusting the latency window dynamically to ensure safe write conditions and reduce latency in data release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the disk drive maintains a fixed latency window for buffer release, then write operation safety is ensured, but latency and performance are degraded
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed latency window to a dynamic buffer release mechanism. The control circuitry continuously monitors servo metric values and adjusts the buffer release timing based on real-time head positioning quality. When servo metrics indicate poor positioning quality, the system extends the buffer release latency to ensure safety; when metrics indicate good positioning quality, the system reduces latency to improve performance. This dynamic adaptation resolves the contradiction between reliability and time loss.
Solution Approach 2:
The patent changes the parameter of buffer release latency from a fixed value to a variable parameter that adjusts based on servo metric conditions. The control circuitry modifies the latency window size according to the measured head positioning quality, allowing the system to optimize the balance between write safety and performance under different operating conditions.
2Productivity
If the disk drive releases buffered data quickly, then latency is reduced and performance improves, but the risk of write operation failures increases under vibration or spindle degradation
Solution Approach 1:
The patent implements feedback by having the control circuitry continuously monitor servo metric values that indicate head positioning quality. This feedback mechanism allows the system to detect degradation in positioning accuracy due to vibration or spindle motor issues and adjust buffer release timing accordingly. The feedback loop ensures that performance optimization does not compromise write reliability, as the system responds to actual positioning conditions rather than using fixed timing.
Solution Approach 2:
The system dynamically adjusts buffer release timing based on real-time servo metric conditions. When positioning quality deteriorates, the system automatically extends the buffer release latency to maintain reliability; when positioning quality is good, the system reduces latency to maximize productivity. This dynamic behavior resolves the contradiction between performance and reliability.
3Reliability
If the disk drive uses a longer buffer release latency window, then write operation safety is improved, but performance and throughput are reduced
Solution Approach 1:
The patent makes the buffer release latency window dynamic rather than fixed. The control circuitry adjusts the window size based on servo metric values that reflect head positioning quality. This allows the system to use longer latency windows only when necessary (poor positioning quality) and shorter windows when positioning is accurate, thereby maintaining reliability while maximizing throughput under good conditions.
Solution Approach 2:
The system changes the latency window parameter from a static value to a dynamic parameter that adapts to positioning conditions. By modifying the latency window size based on servo metrics, the system optimizes the trade-off between write safety and data write throughput under varying operating conditions.
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 reduces latency and improves disk drive performance by dynamically adjusting the buffer release based on servo metric predictions, enhancing the reliability of written data and reducing the likelihood of write operation failures.
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)
Implementation Method 2
An air bearing forms between the head and the disk due to the disk rotating at high speeds
Implementation Method 3
such as a heater which controls fly height through thermal expansion
Implementation Method 4
or a piezoelectric (PZT) actuator
Data Source
AI summary
A disk drive is disclosed wherein N data wedges of write data are buffered in a buffer. After writing at least two of the data wedges to the disk including a first data wedge and a second data wedge, a first servo metric value is measured when reading a first servo sector, and a second servo metric value is predicted based on the first servo metric value, wherein the second servo metric value corresponds to a second servo sector following the first servo sector. When the first servo metric value indicates a safe write condition and the second servo metric value indicates an unsafe write condition, the first data wedge is released from the buffer, and when the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition, the first and second data wedges are released from the buffer.