• Title, Summary, Keyword: file system

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A File System for Large-scale NAND Flash Memory Based Storage System

  • Son, Sunghoon
    • Journal of the Korea Society of Computer and Information
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    • v.22 no.9
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    • pp.1-8
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    • 2017
  • In this paper, we propose a file system for flash memory which remedies shortcomings of existing flash memory file systems. Besides supporting large block size, the proposed file system reduces time in initializing file system significantly by adopting logical address comprised of erase block number and bitmap for pages in the block to find a page. The file system is suitable for embedded systems with limited main memory since it has small in-memory data structures. It also provides efficient management of obsolete blocks and free blocks, which contribute to the reduction of file update time. Finally the proposed file system can easily configure the maximum file size and file system size limits, which results in portability to emerging larger flash memories. By conducting performance evaluation studies, we show that the proposed file system can contribute to the performance improvement of embedded systems.

A Digital Forensic Method for File Creation using Journal File of NTFS File System (NTFS 파일 시스템의 저널 파일을 이용한 파일 생성에 대한 디지털 포렌식 방법)

  • Kim, Tae Han;Cho, Gyu Sang
    • Journal of the Korea Society of Digital Industry and Information Management
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    • v.6 no.2
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    • pp.107-118
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    • 2010
  • This paper proposes a digital forensic method to a file creation transaction using a journal file($LogFile) on NTFS File System. The journal file contains lots of information which can help recovering the file system when system failure happens, so knowledge of the structure is very helpful for a forensic analysis. The structure of the journal file, however, is not officially opened. We find out the journal file structure with analyzing the structure of log records by using reverse engineering. We show the digital forensic procedure extracting information from the log records of a sample file created on a NTFS volume. The related log records are as follows: bitmap and segment allocation information of MFT entry, index entry allocation information, resident value update information($FILE_NAME, $STANDARD_INFORMATION, and INDEX_ALLOCATION attribute etc.).

A New File System for Multimedia Data Stream (멀티미디어 데이터 스트림을 위한 파일 시스템의 설계 및 구현)

  • Lee, Minsuk;Song, Jin-Seok
    • IEMEK Journal of Embedded Systems and Applications
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    • v.1 no.2
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    • pp.90-103
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    • 2006
  • There are many file systems in various operating systems. Those are usually designed for server environments, where the common cases are usually 'multiple active users', 'great many small files' And they assume a big main memory to be used as buffer cache. So the existing file systems are not suitable for resource hungry embedded systems that process multimedia data streams. In this study, we designed and implemented a new file system which efficiently stores and retrieves multimedia data steams. The proposed file system has a very simple disk layout, which guarantees a quick disk initialization and file system recovery. And we introduced a new indexing-scheme, called the time-based indexing scheme, with the file system. With the indexing scheme, the file system maintains the relation between time and the location for all the multimedia streams. The scheme is useful in searching and playing the compressed multimedia streams by locating exact frame position with given time, resulting in reduction of CPU processing and power consumption. The proposed file system and its APIs utilizing the time-based indexing schemes were implemented firstly on a Linux environment, though it is operating system independent. In the performance evaluation on a real DVR system, which measured the execution time of multi-threaded reading and writing, we found the proposed file system is maximum 38.7% faster than EXT2 file system.

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A Study to Improve Recovery Ratio of Deleted File Using the Parsing Algorithm of the HFS + Journal File (HFS+ 저널 파일 파싱 알고리즘을 이용한 삭제된 파일 복구 기법 향상 방안)

  • Bang, Seung Gyu;Jeon, Sang Jun;Kim, Do Hyun;Lee, Sang Jin
    • KIPS Transactions on Computer and Communication Systems
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    • v.5 no.12
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    • pp.463-470
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    • 2016
  • With the growing demand for MAC-based system, the need for digital forensic techniques of these system has been increasing. In the digital forensic analysis process, sometimes analysts have recovered the deleted files when they prove the allegations if system user try to remove the evidence deliberately. Research and analysis that recover the deleted files from a file system constantly been made and HFS+ that is a file system of MAC-based system also has been researched. Carving techniques primarily has been used to recover the deleted file from HFS+ a file system because metadata of folder or file overwrite metadata of a deleted file when file is deleted from a file system on HFS+ characteristic. But if the file content is saved by separated state in a file system, Carving techniques also can't recover the whole or a part of the deleted file. In this paper we describe technique the deleted file recovery technique using HFS+ file system a journal. This technique that is suggested by existing research and analysis result is the technique that recover the deleted file by metadata that is maintained in a journal on HFS+ file system. but this technique excludes specific files and this problem needs to be reformed. In this paper we suggest algorithm that analysis a journal of HFS+ file system in detail. And we demonstrate that the deleted file cat be recovered from the extracted metadata by this algorithm without the excluded file.

A Self-Description File System for NAND Flash Memory (낸드 플래시 메모리를 위한 자기-서술 파일 시스템)

  • Han, Jun-Yeong;Park, Sang-Oh;Kim, Sung-Jo
    • Journal of KIISE:Computing Practices and Letters
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    • v.15 no.2
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    • pp.98-113
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    • 2009
  • Conventional file systems for harddisk drive cannot be applied to NAND flash memory, because the physical characteristics of NAND flash memory differs from those of harddisk drive. To address this problem, various file systems with better reliability and efficiency have also been developed recently. However, those file systems have inherent overheads for updating the file's metadata pages, because those file systems save file's meta-data and data separately. Furthermore, those file systems have a critical reliability problem: file systems fail when either a page in meta-data of a file system or a file itself fails. In this paper, we propose a self-description page technique and In Memory Core File System technique to address these efficiency and reliability problems, and develop SDFS(Self-Description File System) newly. SDFS can be safely recovered, although some pages fail, and improves write and read performance by 36% and 15%, respectively, and reduces mounting time by 1/20 compared with YAFFS2.

Design of an Embedded Linux File System with LZSS Algorithm for the PDA System (LZSS 압축 알고리즘을 적용한 PDA용 Embedded Linux 파일 시스템 설계)

  • Jang Seung-Ju
    • The KIPS Transactions:PartA
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    • v.13A no.2
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    • pp.95-100
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    • 2006
  • I design an Embedded File System in Linux Operating System by applying modified LZSS compressed algorithm. This suggested Compressed File System which is modified file system of the Linux O.S saves the storage space. The compressed file system supports efficient use of storage space. The suggesting file system solves the small space of embedded system. The suggesting file system of this paper gives effect of the large storage space without extending the storage space.

Performance Analysis of Flash File System for Embedded Systems on Linux Environment (리눅스 환경에서 임베디드 시스템을 위한 플래시 파일 시스템의 성능 분석)

  • Choi, Jin-oh
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.302-304
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    • 2013
  • The embedded systems on linux environment, commonly equip a file system as mini hard disk or flash memory to keep data. The types of the file system of the system are various according to it's operating system. Anyway, the more embedded system depends on the file system, the selection of the type of the file system effects more on the performance of the system. This thesis performs the performance benchmark of a FAT and Ext file systems. As the result, it is discussed that what file system is better at which case. These results are helpful at the selection of flash file system of the embedded systems on linux environment.

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Metadata Structrues of Huge Shared Disk File System for Large Files in GIS (GIS에서 대용량 파일을 위한 대용량 공유 디스크 파일시스템의 메타데이터 구조)

  • 김경배;이용주;박춘서;신범주
    • Spatial Information Research
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    • v.10 no.1
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    • pp.93-106
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    • 2002
  • The traditional file system are designed to store and manage fur small size files. So. we cannot process the huge files related with geographic information data using the traditional file system such as unix file system or linux file system. In this paper, we propose new metadata structures and management mechanisms for the large file system in geographic information system. The proposed mechanisms use dynamic multi-level mode for large files and dynamic bitmap for huge file system. We implement the proposed mechanisms in the metadata structures of SANtopia is shared disk huge file system for storage area networks(SAN).

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Performance Comparative Analysis of Flash File System for Embedded Systems on Linux Environment (리눅스 환경에서 임베디드 시스템을 위한 플래시 파일 시스템의 성능 비교 분석)

  • Choi, Jin-Oh
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.1
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    • pp.109-114
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    • 2014
  • Recently the operating system share of linux on embedded system is increasing. The embedded systems on linux environment, commonly equip a file system as mini hard disk or flash memory to keep data. The types of the file system of the system are various according to it's operating system. Anyway, the more embedded system depends on the file system, the selection of the type of the file system effects more on the performance of the system. This thesis performs the performance benchmark of a FAT and Ext file systems which are most popular in embedded system. As the result, it is discussed that what file system is better at which case. These results will be a index at the selection of flash file system of the embedded systems on linux environment.

File Modification Pattern Detection Mechanism Using File Similarity Information

  • Jung, Ho-Min;Ko, Yong-Woong
    • International journal of advanced smart convergence
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    • v.1 no.1
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    • pp.34-37
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    • 2012
  • In a storage system, the performance of data deduplication can be increased if we consider the file modification pattern. For example, if a file is modified at the end of file region then fixed-length chunking algorithm superior to variable-length chunking. Therefore, it is important to predict in which location of a file is modified between files. In this paper, the essential idea is to exploit an efficient file pattern checking scheme that can be used for data deduplication system. The file modification pattern can be used for elaborating data deduplication system for selecting deduplication algorithm. Experiment result shows that the proposed system can predict file modification region with high probability.