Magnetic Disk Drive Head Control for Spiral Track Access
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Solution Overview
Problem
In magnetic disk devices, the spiral data track system requires repeated seek operations for the head to return to the start point after reading or writing data, leading to waiting times due to the radial movement of the head during disk rotation.
Innovation Solution
The head is controlled to follow data tracks in units obtained by subtracting the seek time required for the head to seek the track from a rotation period, allowing it to be positioned at the start point after a seek operation, thereby reducing waiting times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the head follows data tracks in a spiral form from outer circumference towards inner circumference, then sequential access performance is improved, but waiting time increases due to seek operations required when the head returns to the outer circumference
Solution Approach 1:
The controller performs preliminary actions by controlling the head to follow a predetermined data track in units obtained by subtracting seek time from rotation period. This advance positioning ensures the head is already at the correct location when data access is needed, eliminating waiting time after seek operations.
Solution Approach 2:
The system dynamically adjusts the head control units based on the relationship between seek time and rotation period. By making the control unit variable (rotation period minus seek time), the system adapts to the specific timing requirements, allowing the head to be positioned optimally before data access operations.
2Productivity
If the head is controlled to follow data tracks repeatedly, then data access efficiency is improved, but seek operations are required when the head returns to the start point, causing waiting time
Solution Approach 1:
The controller performs preliminary positioning by controlling the head to follow the data track in calculated units (rotation period minus seek time) before data access is needed. This advance action ensures the head is already positioned at the start point when repeated data access operations begin, eliminating waiting time.
Solution Approach 2:
The system maintains continuous useful action by ensuring the head is continuously positioned and ready for data access without interruption. By pre-positioning the head in units of (rotation period - seek time), the system eliminates idle waiting periods and maintains continuous productive operation.
Data Source
AI summary
According to one embodiment, a magnetic disk device includes: a magnetic disk having data spiral tracks extending from an outer circumference towards an inner circumference or from an inner circumference towards an outer circumference; a head configured to read data recorded in the data tracks of the magnetic disk that is rotating and to write data to the data tracks; and a controller configured to control the head to follow a predetermined data track in units obtained by subtracting a seek time required for the head to seek the predetermined data track from a rotation period.