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Online Snapshot Method based on Directory and File Change Tracking for Virtual File System

가상파일시스템에서 디렉토리 및 파일 변경 추적에 기반한 온라인 스냅샷 방법

  • 김진수 (한국교통대학교 컴퓨터공학전공) ;
  • 송석일 (한국교통대학교 컴퓨터공학전공) ;
  • 신재룡 (광주보건대학교 보건행정과)
  • Received : 2019.04.23
  • Accepted : 2019.05.03
  • Published : 2019.05.28

Abstract

Storage snapshot technology allows to preserve data at a specific point in time, and recover and access data at a desired point in time. It is an essential technology for storage protection application. Existing snapshot methods have some problems in that they dependent on storage hardware vendor, file system or virtual block device. In this paper, we propose a new snapshot method for solving the problems and creating snapshots on-line. The proposed snapshot method uses a method of extracting the log records of update operations at the virtual file system layer to enable the snapshot method to operate independently on file systems, virtual block devices, and storage hardwares. In addition, the proposed snapshot mehod creates and manages snapshots for directories and files without interruption to the storage service. Finally, through experiments we measure the snapshot creation time and the performance degradation caused by the snapshot.

Keywords

Storage;Snapshot;Virtual File System;Recovery

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그림 1. 개발하는 스냅샷 방법의 구조

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그림 2. redo_log() 의 필요성을 보여주는 사례

CCTHCV_2019_v19n5_417_f0003.png 이미지

그림 3. 스냅샷 테이블과 디렉토리 테이블 구조

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그림 4. write 연산에 대한 CoW 처리 절차

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그림 5. append 연산 처리 절차

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그림 6. rename 연산에 대한 CoW 처리 절차

CCTHCV_2019_v19n5_417_f0007.png 이미지

그림 7. rename 된 파일에 대한 write 연산에 대한 CoW처리 절차

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그림 8. 읽기-쓰기 비율에 따른 IOPS 비교

표 1. 스냅샷 생성 알고리즘

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표 2. 실험환경

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Acknowledgement

Supported by : 광주보건대학교

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