Disk Data Refresh Using Segmented Save Areas

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Solution Overview

Problem

In magnetic disk drives, data refreshing is necessary to counteract data deterioration due to write fringing and head positioning errors, but existing methods risk data loss if the power supply is interrupted during the refreshing process, especially when using a specific track as a save area, which requires multiple seek operations, reducing efficiency and increasing the risk of data loss.

Innovation Solution

The method involves partitioning tracks into segments and using the first segment as a temporary save area for data from other segments, reducing the number of long-distance seek operations and ensuring data integrity by adding headers and footers for validation, allowing for efficient data refreshing and power shutdown recovery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a specific track on the disk is used as a save area for temporarily saving data during refresh operations, then data integrity is improved (data loss is prevented), but the number of seek operations increases (efficiency deteriorates)

Engineering Contradiction:

Improvedata integrityVSAvoidrefresh efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The disk is divided into multiple segments, with the first segment designated as a save area and the remaining segments as work areas. This segmentation allows data to be temporarily stored in the first segment during refresh operations, preventing data loss while enabling efficient sequential processing of data in the work areas without requiring frequent long-distance seeks to a separate save area.

Inventive Principle:

Principle #1Segmentation

2Speed

If data is read from a track and temporarily stored in RAM for rewriting, then refresh operation speed is improved, but data loss risk increases (if power is shut down during rewrite)

Engineering Contradiction:

Improverefresh operation speedVSAvoiddata loss risk

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

Before performing the rewrite operation to the target track, the data is first saved to the first segment (save area). This preliminary action ensures that if power is shut down during the subsequent rewrite operation, the original data can be restored from the save area, thus preventing data loss while maintaining fast RAM-based processing.

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If track pitch is made narrower to increase storage capacity, then storage density is improved, but write fringing effects worsen (data deterioration increases)

Engineering Contradiction:

Improvestorage capacityVSAvoidwrite fringing

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The invention creates a copy of the data to be refreshed and stores it in the first segment before performing the rewrite operation. This copying mechanism allows the system to handle write fringing effects by having a backup copy available, enabling safe retry operations if data deterioration occurs during the narrow-track write process.

Inventive Principle:

Principle #26Copying

Data Source

PatentUS8154814B2Method of refreshing data stored on a disk

Publication Date: 2012.04.10 KK TOSHIBA

AI summary

According to one embodiment, a disk comprises an area which comprises a plurality of data tracks and is partitioned into a first segment and a plurality of second segments. A controller detects that a segment to be refreshed next is one of the plurality of second segments. The controller saves data stored in the one of the plurality of second segments into the first segment when a segment to be refreshed next is the one of the plurality of second segments.