Virtualized File System Interconnect for Legacy Migration

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Solution Overview

Problem

Existing data storage systems face challenges in seamlessly transitioning from legacy file servers to new ones without disrupting user access, especially when upgrading to manage more file systems, improve I/O performance, or adopt new storage technologies, while maintaining existing file system structures and user data integrity.

Innovation Solution

A method and apparatus for creating a virtualized file system by interconnecting a new file system managing unit with a legacy one, enabling indirect access through the new unit, which allows for on-demand and automatic virtualization of the legacy file system, allowing clients to access the legacy system without interruption by creating virtual directories and external link objects, and migrating user data incrementally.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a new file system managing unit is interconnected between client computers and a legacy second file system managing unit, then client access to the legacy file system is enabled without interruption, but the system complexity increases due to the additional managing unit and virtualization layer

Engineering Contradiction:
Improvecontinuous availabilityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The first file system managing unit acts as an intermediary between client computers and the legacy second file system managing unit. It creates a virtualized file system that transparently mediates all access requests, allowing clients to access the legacy file system through the new managing unit without direct connection, thereby enabling seamless transition while maintaining continuous availability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a virtualized copy of the legacy file system structure in the new file system managing unit. This virtualized file system replicates the directory structure and file metadata of the legacy system, allowing clients to access data through the new managing unit while the actual data remains in the legacy system, reducing complexity by abstracting the transition mechanism

Inventive Principle:
Principle #26Copying

2Manufacturing precision

If virtualization of the legacy file system is performed completely before migration, then data integrity is ensured, but the downtime for user access increases during the virtualization phase

Engineering Contradiction:
Improvedata integrityVSAvoiddowntime
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary virtualization of the file system structure (directories and metadata) before migrating user data. The virtualized directory structure is created in advance in the new file system managing unit, allowing clients to immediately access the virtualized structure while data migration proceeds in the background, thus minimizing downtime while ensuring data integrity through structured virtualization

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The virtualization process is segmented into distinct phases: first virtualizing the directory structure and metadata, then migrating user data in subsequent phases. This segmentation allows the file system structure to be prepared and made accessible immediately, while data migration occurs separately without blocking client access to the virtualized structure, reducing overall downtime

Inventive Principle:
Principle #1Segmentation

3Loss of time

If user data is migrated incrementally during the virtualization phase, then downtime is minimized, but the system complexity increases due to overlapping phases and coordination requirements

Engineering Contradiction:
ImprovedowntimeVSAvoidcoordination complexity
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The patent implements dynamic phase management where virtualization and migration phases can overlap and proceed concurrently. The system dynamically adjusts the progression of data migration based on available resources and client access patterns, allowing flexible coordination that minimizes downtime while managing complexity through adaptive control mechanisms

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2836901B1Method and apparatus for virtualization of a file system, data storage system for virtualization of a file system, and file server for use in a data storage system
Publication Date: 2017.09.06 HITACHI DATA SYST ENG UK
  • EP2836901B1 patent drawingFigure 1A~1B
  • EP2836901B1 patent drawingFigure 1C~1D
  • EP2836901B1 patent drawingFigure 2~3

AI summary

The present invention relates to a method and an apparatus for providing a virtualized file system enabling indirect access to a second file system in a data storage system comprising a plurality of client computers 100 and a second file system managing unit 410 for managing the second file system and enabling client access to the second file system, the method comprising interconnecting a first file system managing unit 310 between the plurality of client computers 100 and the second file system managing unit 410, creating a first directory /root in a first file system managed by the first file system managing unit 310, associating a first directory /root of the second file system with the first directory /root of the first file system, enabling on-demand virtualization of the second file system by the first file system managing unit 310 based on client requests received from the client computers 100 at the first file system managing unit 310 and based on the association between the first directory of the first file system and the first directory of the second file system, and enabling indirect client access to the second file system through the first file system.