• Title/Summary/Keyword: In-memory file system

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Prefetching System based on File Access Pattern Applicable to Multimedia Prefetching Scheme (멀티미디어 선반입에 적용 가능한 파일 액세스 패턴 기반의 선반입 시스템)

  • 황보준형;서대화
    • Journal of Korea Multimedia Society
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    • v.4 no.6
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    • pp.489-499
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    • 2001
  • This paper presents the SIC(Size-Interval-Count) prefetching system that can record the file access patterns of applications within a relatively small space of memory based on the repetitiveness of the file access patterns. The SICPS(SIC Prefetching System) is based on knowledge-based prefetching methods which includes high correctness in predicting future accesses of applications. The proposed system then uses the recorded file access patterns, referred to as "SIC access pattern information", to correctly predict the future accesses of the applications. The proposed prefetching system improved the response time by about 40% compared to the general file system and showed remarkable memory efficiency compared to the previously knowledge-based prefetching methods.

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The Study of the Implementation of the Boot System Using CF(Compact Flash) memory card 2. Implementation of the Boot Loader (CF(Compact Flash)메모리 카드를 이용한 부트 시스템 구현에 관한 연구 2. 부트로더의 구현)

  • 이광철;김영길
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.8 no.1
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    • pp.115-122
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    • 2004
  • This paper describe the implementation or the boot loader for the boot system using of memory card. This boot roader consist of the system initialization, CF card checking, CF memory card checking, file system and the program relocator. This boot loader increase the system stability with program consistency checking algorithm in the read phase from the CF memory card. And this system have the compatibility in CF memory card file system, so system manufacturing productivity increase.

In-Memory File System Backed by Cloud Storage Services as Permanent Storages (클라우드 스토리지를 최종 저장 장치로 사용하는 인메모리 파일 시스템)

  • Lee, Kyungjun;Kim, Jiwon;Ryu, Sungtae;Han, Hwansoo
    • Journal of KIISE
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    • v.43 no.8
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    • pp.841-847
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    • 2016
  • As network technology advances, a larger number of devices are connected through the Internet. Recently, cloud storage services are gaining popularity, as they are convenient to access anytime and anywhere. Among cloud storage services, object storage is the representative one due to their characteristics of low cost, high availability, and high durability. One limitation of object storage services is that they can access data on the cloud only through the HTTP-based RESTful APIs. In our work, we resolve this limitation with the in-memory file system which provides a POSIX interface to the file system users and communicates with cloud object storages with RESTful APIs. In particular, our flush mechanism is compatible with existing file systems, as it is based on the swap mechanism of the Linux kernel. Our in-memory file system backed by cloud storage reduces the performance overheads and shows a better performance than S3QL by 57% in write operations. It also shows a comparable performance to tmpfs in read operations.

A Performance Analysis of I/O Scheduler for NAND Flash File System (NAND 플래시 파일시스템의 I/O 스케줄러 성능분석)

  • Lee, Yeongseok;Lee, Changhee;Chung, Kyungho;Kim, Yonghwan;Ahn, Kwangseon
    • Journal of Korea Society of Industrial Information Systems
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    • v.18 no.2
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    • pp.27-34
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    • 2013
  • NAND Flash Memory has been used in several devices by low cost and high capacity, and the demand for mass NAND Flash Memory has increased due to the multimedia extension of mobile devices. The JFFS2, NILFS2, and YAFFS2 file systems are used mainly in NAND Flash Memory. In this paper, the performance of Sequential read/write of the 3 file systems are analyzed for the 4 I/O schedulers : CFQ(Complete Fair Queuing) I/O scheduler, NOOP(No Operation) I/O scheduler, Anticipatory I/O scheduler, and Deadline I/O scheduler. In JFFS2 file system, Anticipatory I/O scheduler has the best performance by 8% decreasing speed in writing time and 1.5% decreasing speed in reading time compared to the other I/O scheduler. In YAFFS2 file system, it results are similar to performance in reading and writing for the 4 I/O schedulers. In NILFS2 file system, NOOP I/O scheduler has 2% faster in writing and Deadline I/O scheduler has 6% faster in reading than other I/O schedulers.

A Design for File Access in Storage Class Memory-based Computer Systems (스토리지 클래스 메모리에서의 파일 접근 설계)

  • Park, Sungmin;Won, Youjip;Kang, Sooyong
    • Journal of Digital Contents Society
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    • v.14 no.2
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    • pp.247-254
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    • 2013
  • Storage Class Memory(SCM), such as PRAM, FRAM and MRAM, are expected to be comparable to DRAM in terms of access speed and to Flash memory in terms of capacity in a near future. In this paper, assuming that not only the secondary storage (HDD or Flash memory) but also the primary memory (DRAM) will be replaced by SCM in the future computer systems, we propose an efficient file access framework for the SCM based computer systems. The proposed framework do not assign exclusive area in the SCM to the file system and uses various memory-related techniques, such as unified data access path, zero-copy data read using file mapping, copy-on-write, and multiple page pre-faulting for file management. Based on the preliminary experimental results, we could conclude that the proposed framework can be an efficient baseline for designing a new operating system for the SCM based computer systems.

The Architecture of the Flash Memory Storage System using Page Delete Information (페이지 삭제정보를 활용하는 플래시 저장장치의 구조)

  • Jung, Ho-Young;Park, Sung-Min;Kang, Soo-Yong;Cha, Jae-Hyuk
    • Journal of KIISE:Computing Practices and Letters
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    • v.15 no.12
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    • pp.958-962
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    • 2009
  • Flash memory, which replaces hard disk recently, has different physical characteristics with hard disk. For the performance of flash memory based storage system, many researches over OS and file system layers has been doing. In this paper, we propose the architecture of flash memory based storage which uses information of page invalidation when file deletion occurs from upper layer. Also, we evaluate the performance of proposed system. Proposed system effectively increases IO performance by using page invalidation information to block merge and wear leveling algorithms.

An Optimized File System for SSD (SSD를 위한 최적화 파일시스템)

  • Park, Je-Ho
    • Journal of the Semiconductor & Display Technology
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    • v.9 no.2
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    • pp.67-72
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    • 2010
  • Recently increasing application of flash memory in mobile and ubiquitous related devices is due to its non-volatility, fast response time, shock resistance and low power consumption. Following this trend, SSD(Solid State Disk) using multiple flash chips, instead of hard-drive based storage system, started to widely used for its advantageous features. However, flash memory based storage subsystem should resolve the performance bottleneck for writing in perspective of speed and lifetime according to its disadvantageous physical property. In order to provide tangible performance, solutions are studied in aspect of reclaiming of invalid regions by decreasing the number of erasures and distributing the erasures uniformly over the whole memory space as much as possible. In this paper, we study flash memory recycling algorithms with multiple management units and demonstrate that the proposed algorithm provides feasible performance. The proposed method utilizes the partitions of the memory space by utilizing threshold values and reconfigures the management units if necessary. The performance of the proposed policies is evaluated through a number of simulation based experiments.

File System for Performance Improvement in Multiple Flash Memory Chips (다중 플래시 메모리 기반 파일시스템의 성능개선을 위한 파일시스템)

  • Park, Je-Ho
    • Journal of the Semiconductor & Display Technology
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    • v.7 no.3
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    • pp.17-21
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    • 2008
  • Application of flash memory in mobile and ubiquitous related devices is rapidly being increased due to its low price and high performance. In addition, some notebook computers currently come out into market with a SSD(Solid State Disk) instead of hard-drive based storage system. Regarding this trend, applications need to increase the storage capacity using multiple flash memory chips for larger capacity sooner or later. Flash memory based storage subsystem should resolve the performance bottleneck for writing in perspective of speed and lifetime according to its physical property. In order to make flash memory storage work with tangible performance, reclaiming of invalid regions needs to be controlled in a particular manner to decrease the number of erasures and to distribute the erasures uniformly over the whole memory space as much as possible. In this paper, we study the performance of flash memory recycling algorithms and demonstrate that the proposed algorithm shows acceptable performance for flash memory storage with multiple chips. The proposed cleaning method partitions the memory space into candidate memory regions, to be reclaimed as free, by utilizing threshold values. The proposed algorithm handles the storage system in multi-layered style. The impact of the proposed policies is evaluated through a number of experiments.

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RFFS : Design of a Reliable NAND Flash File System for Embedded system (임베디드 시스템을 위한 신뢰성 있는 NAND 플래시 파일 시스템의 설계)

  • Lee Tae-hoon;Park Song-hwa;Kim Tae-hoon;Lee Sang-gi;Lee Joo-Kyong;Chung Ki-Dong
    • The KIPS Transactions:PartA
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    • v.12A no.7 s.97
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    • pp.571-582
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    • 2005
  • NAND flash memory has advantages of non-volatility, little power consumption and fast access time. However, it suffers from inability that dose not provide to update-in-place and the erase cycle is limited. Moreover, the unit of read and write operations is a page. A NAND flash file system called YAFFS has been proposed. But YAFFS has several problems to be addressed. In this paper, the Reliable Flash File System(RFFS) for NAND flash memory is designed and evaluated. In designing a file system the following four issues must be considered in particular for the design: (i) to minimize a repairing time when the system fault occurs, (ii) to balance the number of block erase operations by offering wear leveling policy, and (iii) to reduce turnaround time of memory operations by reducing the amount of data written. We demonstrate and evaluate the performance of the proposed schemes.

Design and Evaluation of a High-performance Journaling Scheme for Non-volatile Memory (비휘발성 메모리를 고려한 고성능 저널링 기법 설계 및 평가)

  • Han, Hyuck
    • The Journal of the Korea Contents Association
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    • v.20 no.8
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    • pp.368-374
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    • 2020
  • Journaling file systems (JFS) manage changes of file systems not yet committed in a data structure known as a journal to restore the file system in the event of an unexpected failure. Extra write operations required for journaling negatively affect the performance of JFS. The high-performance and byte-addressable non-volatile memory (NVM) was expected to easily mitigate these performance problems by providing NVM space as journal storage. However, even with such non-volatile memory technologies, performance problems still arise due to scalability problems inherent in processing transactions of JFS. To solve this problem, we proposes a technique for processing file system transactions for scalable performance. To this end, lock-free data structures are used and multiple I/O requests are allowed to simultaneously be processed on high-performance storage devices with multiple I/O channels. We evaluate the file system with the proposed technique by comparing the original ext4 file system and the recent proposed NVM-based journaling file system on a multi-core server, and experimental results show that our file system has better performance (up-to 2.9/2.3 times) than the original ext4 file system and the recent NVM-based journaling file system, respectively.