Multi-Actuator Magnetic Disk Write Stop Control
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Solution Overview
Problem
Magnetic disk devices with multiple actuators face challenges in quickly stopping write operations due to the time required for each actuator to detect and adjust the head position, leading to potential data loss during vibrations or shocks.
Innovation Solution
A magnetic disk device configuration with multiple actuators and controllers that independently control write operations based on data sector position error information from both servo and data sectors, allowing for simultaneous stoppage of write operations across multiple heads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple actuators are used to independently control head positions, then head positioning capability is improved, but the time required to detect position errors and stop write operations increases
Solution Approach 1:
The patent applies preliminary action by continuously monitoring position error signals from data sectors before write operations are affected by vibrations or shocks. The system proactively detects position errors and prepares to stop write operations in advance, rather than reacting after damage occurs. This is achieved by reading data sectors, demodulating position error signals, and comparing them against thresholds continuously during normal operation.
Solution Approach 2:
The patent implements feedback mechanisms by continuously reading data sectors to obtain position error signals, comparing these signals against predetermined thresholds, and automatically stopping write operations when thresholds are exceeded. The feedback loop ensures that write operations are halted promptly when head position deviations indicate potential data loss risks, transforming the multi-actuator system's detection capability into rapid protective action.
2Speed
If a large threshold value is used for head position to ensure quick detection, then response speed is improved, but measurement precision deteriorates
Solution Approach 1:
The patent applies parameter changes by using different threshold values for different actuators based on their specific characteristics and operational conditions. Rather than using a single large threshold for all actuators, the system configures appropriate thresholds for each actuator-head-disk combination, allowing optimized balance between response speed and measurement precision for each component while maintaining overall system performance.
3Adaptability or versatility
If each actuator independently detects position errors, then control flexibility is improved, but coordination time among multiple actuators increases
Solution Approach 1:
The patent merges the independent actuator control functions into a unified control architecture where all actuators are coordinated through a central controller that processes position error signals from all heads simultaneously. This integration allows independent detection capabilities to be maintained while eliminating coordination delays through centralized decision-making and simultaneous stoppage commands to all actuators when position errors are detected.
Data Source
AI summary
According to one embodiment, a magnetic disk device includes a first disk including a first data sector, a second disk including a second data sector, a first head including a first read head, a second head including a second read head, a first controller that stops write operations of both the first head and the second head based on first data sector position error information obtained by reading and demodulating the first data sector by using the first read head, and a second controller that stops the write operations of both the first head and the second head based on second data sector position error information obtained by reading and demodulating the second data sector by using the second read head.