Snapshot Synchronization in Distributed Shared File Systems

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Solution Overview

Problem

In distributed shared file systems, creating snapshots disrupts system operations, leading to inefficiencies and potential data loss due to the need to suspend all application programs during the snapshot process, which is particularly challenging in environments with multiple clients and shared data.

Innovation Solution

A method that synchronizes snapshot operations across domains, writes pending write requests to memory to suspend write operations, and generates a snapshot file representing the current state of the system without halting system operations, using a 'single-write' technique and page files to manage mapping information efficiently.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If data is copied to create a snapshot, then data integrity is ensured, but system operations must be suspended leading to decreased productivity

Engineering Contradiction:

Improvedata integrityVSAvoidsystem operation efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system performs preliminary actions by flushing pending write requests to stable storage before creating the snapshot. This ensures data integrity is established in advance, allowing the snapshot to be created without suspending ongoing system operations, thus maintaining productivity while ensuring reliability

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If all write requests are suspended during snapshot creation, then snapshot accuracy is improved, but system efficiency deteriorates

Engineering Contradiction:

Improvesnapshot accuracyVSAvoidsystem efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

Write requests are suspended only temporarily to flush pending writes to stable storage before the snapshot is created. This preliminary flushing action ensures snapshot accuracy by capturing consistent data state, while the suspension is brief enough to minimize impact on overall system efficiency

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system maintains continuity of useful actions by allowing most system operations to continue during snapshot creation. Only the specific write flushing operation is temporarily suspended, while other read operations and system functions continue uninterrupted, preserving overall system efficiency while achieving accurate snapshots

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If snapshots are created by copying data, then data backup is achieved, but disk space consumption increases

Engineering Contradiction:

Improvedata backupVSAvoiddisk space usage

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The invention extracts only the essential snapshot data to a separate snapshot file system, leaving the original production file system intact. This allows data backup to be achieved while minimizing disk space consumption in the production system, as snapshots are stored separately and can be managed independently

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS7913046B2Method for performing a snapshot in a distributed shared file system

Publication Date: 2011.03.22 DELL GLOBAL - SINGAPORE BRANCH

AI summary

A method for performing a snapshot in a distributed shared file system (DSFS) is provided. The method includes synchronizing a snapshot operation among a plurality of domains of the DSFS; writing pending write requests to a memory to suspend write operations for the domains of the DSFS; and after the writing the pending write requests, generating a snapshot file comprising data items representing a current state of the DSFS.