Magnetic Disk Controller Dual-Scale Command Reordering

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Solution Overview

Problem

Magnetic disk devices face inefficiencies in accessing data due to the need for reordering operations when handling commands for both Shingled Magnetic Recording (SMR) and Conventional Magnetic Recording (CMR) methods, leading to increased total moving distance and time for the magnetic head.

Innovation Solution

A magnetic disk device with a controller that dynamically allocates SMR and CMR storage areas, providing numerical information on respective scales to unify section access, allowing for efficient reordering of commands to minimize the magnetic head's moving distance by converting section numbers between SMR and CMR scales.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If reordering operation is performed to optimize access order, then access efficiency is improved, but time required for reordering operation increases

Engineering Contradiction:

Improveaccess efficiencyVSAvoidtime required for reordering operation

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The controller pre-provides numerical information on both first scale (SMR scale) and second scale (CMR scale) to all sections during initialization. When commands are received, the controller can immediately compare and reorder commands using the pre-prepared numerical information without performing time-consuming conversions during command processing, thus reducing reordering time while maintaining access efficiency

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The numerical information on dual scales acts as an intermediary that facilitates direct comparison between SMR and CMR sections. By providing both scale representations, the controller can efficiently determine access order without complex real-time calculations, resolving the contradiction between optimization quality and processing time

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If separate numerical information is provided for SMR and CMR sections, then storage area management flexibility is improved, but device complexity increases

Engineering Contradiction:

Improvestorage area management flexibilityVSAvoidcontroller complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The controller is designed to provide numerical information on multiple scales simultaneously, making it universally compatible with both SMR and CMR storage methods. This multi-functionality allows the same controller structure to manage different storage areas with different characteristics without requiring separate control mechanisms, thus improving flexibility while controlling complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The controller divides the storage area management into separate sections, each with numerical information on both scales. This segmentation allows independent management of SMR and CMR areas while using a unified dual-scale numerical information system, reducing overall controller complexity through modular organization

Inventive Principle:

Principle #1Segmentation

3Productivity

If magnetic head moves to access both SMR and CMR storage areas, then data access completeness is improved, but total moving distance increases

Engineering Contradiction:

Improvedata access completenessVSAvoidtotal moving distance

Core Design Contradiction:

ProductivityVSLength of moving object

Solution Approach 1:

The controller merges the access planning for SMR and CMR storage areas by converting all section identifiers to a unified scale basis. This allows the controller to generate an integrated access sequence that combines both storage area types, optimizing the magnetic head's movement path to access all required data while minimizing total moving distance

Inventive Principle:

Principle #5Merging (Combining)

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 the time required for reordering operations and improves access efficiency by allowing the magnetic head to move in a shorter distance, optimizing data access across both SMR and CMR storage areas.

Implementation Method 1

a magnetic disk having a recording surface; a magnetic head that accesses the recording surface

Methodology Applied

Scientific EffectMagnetic recording: Magnetism

Data Source

PatentUS11886753B2Magnetic disk device and method of ordering commands based on selected scale

Publication Date: 2024.01.30 KK TOSHIBA

AI summary

A controller provides a plurality of first sections with numerical information on a first scale. The plurality of first sections are obtained by dividing a recording surface of a magnetic disk in units of first memory areas in each of which a first volume of data can be written by an SMR method. The first scale corresponds to a sequence of the first sections. The controller provides a plurality of second sections with numerical information on a second scale. The plurality of second sections are obtained by dividing the recording surface of the magnetic disk in units of second memory areas in each of which the first volume of data can be written by a CMR method. The second scale corresponds to a sequence of the second sections. The controller executes a plurality of commands in order based on a numerical information on the first scale or the second scale.