Magnetic Disk Device Dynamic Region Allocation

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Solution Overview

Problem

Magnetic disk devices face issues when a sector in the user region becomes defective, leading to unfeasible data read operations, and when the alternative region is fully utilized, new data reception is prohibited, resulting in a write-protect mode where data cannot be written.

Innovation Solution

The magnetic disk device employs a control circuit that reallocates space from the media cache region to the alternative region, allowing continuous data reception by substituting defective sectors and extending the operational period by adding free regions to the alternative region when no free space is available.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the alternative region is used to store data for defective sectors, then data integrity is maintained, but the operational period ends when the alternative region is full

Engineering Contradiction:

Improvedata integrityVSAvoidoperational period

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent implements dynamic region allocation where the boundary between media cache region and alternative region is not fixed but can be adjusted during operation. When the alternative region becomes full, the system dynamically reallocates space from the media cache region to expand the alternative region, thereby extending the operational period while maintaining data integrity through continued defect substitution

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the allocation parameter (region size) dynamically based on operational conditions. By monitoring the fill status of the alternative region and adjusting the partition between media cache and alternative regions, the system optimizes both data integrity protection and operational duration

Inventive Principle:

Principle #35Parameter changes

2Duration of action of moving object

If the alternative region is expanded to extend operational period, then data reception continues, but media cache region is reduced

Engineering Contradiction:

Improveoperational periodVSAvoidmedia cache capacity

Core Design Contradiction:

Duration of action of moving objectVSQuantity of substance

Solution Approach 1:

The patent employs dynamic region allocation where the boundary between media cache region and alternative region is adjustable during operation. When the alternative region becomes full, the system dynamically reallocates space from the media cache region to expand the alternative region, thereby extending the operational period while maintaining data integrity through continued defect substitution

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10650857B2Magnetic disk device and control method

Publication Date: 2020.05.12 KK TOSHIBA

AI summary

According to one embodiment, a magnetic disk device includes a disk medium which has a first region, a second region, and a redundant third region, and a control circuitry. The first region is a region to which first data received from a host is written. The second region is a region to which the first data is temporarily written before the first data is written to the first region. The control circuitry executes defect detection to the first region. Upon detecting a defect, the control circuitry substitutes a first location having the defect in the first region with a second location in the third region. Depending on a total size of free regions of the third region, the control circuitry reallocates a fourth region from the second region to the third region. The fourth region is part or all of the second region.