Magnetic Disk Controller Adjusts Write Limits via Invalid Parity Sectors
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Solution Overview
Problem
Adjacent track interference (ATI) accumulates with repeated writing on magnetic disk tracks, making it difficult to read data from adjacent tracks, necessitating frequent rewriting and requiring pre-adjustment of a guaranteed number of writes before shipment to prevent data loss.
Innovation Solution
A magnetic disk device with a controller that adjusts the guaranteed number of writes by using an invalid parity sector, allowing for dynamic adjustment of writing limits based on the availability of valid parity sectors, thereby optimizing writing times and preventing ATI failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the guaranteed number of writes is increased to prevent ATI failures, then data readability is improved, but writing productivity decreases due to frequent rewriting operations
Solution Approach 1:
The controller performs preliminary determination of the guaranteed number of writes by detecting invalid parity sectors before actual data writing operations. This advance preparation allows the system to establish writing limits proactively, preventing ATI failures before they occur and avoiding mid-operation interruptions that would reduce productivity
Solution Approach 2:
The system uses its own parity sector validation mechanism to automatically determine writing limits without requiring external intervention or complex external systems. The controller self-manages the determination process by monitoring parity sector validity and autonomously adjusting the guaranteed number of writes based on detected invalid sectors
2Productivity
If the guaranteed number of writes is adjusted frequently to optimize performance, then writing productivity improves, but device complexity increases
Solution Approach 1:
The controller autonomously determines the guaranteed number of writes by monitoring parity sector validity without requiring complex external control systems or manual intervention. This self-service approach simplifies the overall device architecture while enabling dynamic optimization of writing performance
Solution Approach 2:
The system implements a feedback mechanism where the controller continuously monitors parity sector validity and uses this information to dynamically adjust the guaranteed number of writes. This closed-loop control enables automatic optimization of writing performance based on actual device state without increasing overall system complexity
3Productivity
If invalid parity sectors are used for writing operations, then writing productivity improves, but data reliability deteriorates due to potential ATI failures
Solution Approach 1:
The system converts the presence of invalid parity sectors from a harmful condition into a beneficial opportunity. Instead of avoiding writes to tracks with invalid parity sectors, the controller identifies these sectors and determines guaranteed write numbers based on their invalidity, allowing productive use of previously unusable storage capacity while maintaining data reliability through calculated writing limits
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 improves the magnetic disk device's performance by dynamically adjusting writing limits, reducing the risk of ATI failures and maintaining data readability, even after shipment, by utilizing invalid parity sectors for writing without affecting the device's operation.
Implementation Method 1
a magnetic head that executes writing/reading to/from the magnetic disk
Data Source
AI summary
A magnetic disk device according to one embodiment includes a magnetic disk on which multiple tracks are provided, a magnetic head, and a controller. At least one of the multiple tracks includes first sectors and a second sector. Each of the first sectors stores data segments. The second sector stores a parity for error correction. The magnetic head executes writing/reading to/from the magnetic disk. The controller executes processing of adjusting a guaranteed number of times by using a second sector being invalid. The guaranteed number of times indicates a number of times of writing for guaranteeing reading from an adjacent track.