The Experts below are selected from a list of 2091 Experts worldwide ranked by ideXlab platform

Wolfgang Reif - One of the best experts on this subject based on the ideXlab platform.

  • VSTTE - Inside a Verified Flash File System: Transactions and Garbage Collection
    Lecture Notes in Computer Science, 2016
    Co-Authors: Gidon Ernst, Jorg Pfahler, Gerhard Schellhorn, Wolfgang Reif
    Abstract:

    The work presented here addresses a long-standing conceptual gap in Flash File System verification: We map an abstract graph-based representation down to the flat blocks of bytes of the storage medium. Specifically, we consider grouping of File System objects into atomic transactions together with layout, allocation and garbage collection of on-Flash storage space. Two major concerns guide the design and verification: proper handling of errors and, more importantly, guaranteed recovery from unexpected power cuts. Finding useful specifications of intermediate interfaces to address these concerns realistically dominates the verification effort.

  • inside a verified Flash File System transactions and garbage collection
    Verified Software: Theories Tools Experiments, 2015
    Co-Authors: Gidon Ernst, Jorg Pfahler, Gerhard Schellhorn, Wolfgang Reif
    Abstract:

    The work presented here addresses a long-standing conceptual gap in Flash File System verification: We map an abstract graph-based representation down to the flat blocks of bytes of the storage medium. Specifically, we consider grouping of File System objects into atomic transactions together with layout, allocation and garbage collection of on-Flash storage space. Two major concerns guide the design and verification: proper handling of errors and, more importantly, guaranteed recovery from unexpected power cuts. Finding useful specifications of intermediate interfaces to address these concerns realistically dominates the verification effort.

  • development of a verified Flash File System
    ABZ 2014 Proceedings of the 4th International Conference on Abstract State Machines Alloy B TLA VDM and Z - Volume 8477, 2014
    Co-Authors: Gerhard Schellhorn, Gidon Ernst, Jorg Pfahler, Dominik Haneberg, Wolfgang Reif
    Abstract:

    This paper gives an overview over the development of a formally verified File System for Flash memory. We describe our approach that is based on Abstract State Machines and incremental modular refinement. Some of the important intermediate levels and the features they introduce are given. We report on the verification challenges addressed so far, and point to open problems and future work. We furthermore draw preliminary conclusions on the methodology and the required tool support.

  • ABZ - Development of a Verified Flash File System
    Lecture Notes in Computer Science, 2014
    Co-Authors: Gerhard Schellhorn, Gidon Ernst, Jorg Pfahler, Dominik Haneberg, Wolfgang Reif
    Abstract:

    This paper gives an overview over the development of a formally verified File System for Flash memory. We describe our approach that is based on Abstract State Machines and incremental modular refinement. Some of the important intermediate levels and the features they introduce are given. We report on the verification challenges addressed so far, and point to open problems and future work. We furthermore draw preliminary conclusions on the methodology and the required tool support.

  • ABZ - Modular Refinement for Submachines of ASMs
    Lecture Notes in Computer Science, 2014
    Co-Authors: Gidon Ernst, Jorg Pfahler, Gerhard Schellhorn, Wolfgang Reif
    Abstract:

    We describe and formalize a compositional, contract-based submachine refinement for a variant of Abstract State Machines. We motivate the approach by models of the Flash File System case study, where it is infeasible to refine a complete machine as a whole.

Gidon Ernst - One of the best experts on this subject based on the ideXlab platform.

  • VSTTE - Inside a Verified Flash File System: Transactions and Garbage Collection
    Lecture Notes in Computer Science, 2016
    Co-Authors: Gidon Ernst, Jorg Pfahler, Gerhard Schellhorn, Wolfgang Reif
    Abstract:

    The work presented here addresses a long-standing conceptual gap in Flash File System verification: We map an abstract graph-based representation down to the flat blocks of bytes of the storage medium. Specifically, we consider grouping of File System objects into atomic transactions together with layout, allocation and garbage collection of on-Flash storage space. Two major concerns guide the design and verification: proper handling of errors and, more importantly, guaranteed recovery from unexpected power cuts. Finding useful specifications of intermediate interfaces to address these concerns realistically dominates the verification effort.

  • inside a verified Flash File System transactions and garbage collection
    Verified Software: Theories Tools Experiments, 2015
    Co-Authors: Gidon Ernst, Jorg Pfahler, Gerhard Schellhorn, Wolfgang Reif
    Abstract:

    The work presented here addresses a long-standing conceptual gap in Flash File System verification: We map an abstract graph-based representation down to the flat blocks of bytes of the storage medium. Specifically, we consider grouping of File System objects into atomic transactions together with layout, allocation and garbage collection of on-Flash storage space. Two major concerns guide the design and verification: proper handling of errors and, more importantly, guaranteed recovery from unexpected power cuts. Finding useful specifications of intermediate interfaces to address these concerns realistically dominates the verification effort.

  • development of a verified Flash File System
    ABZ 2014 Proceedings of the 4th International Conference on Abstract State Machines Alloy B TLA VDM and Z - Volume 8477, 2014
    Co-Authors: Gerhard Schellhorn, Gidon Ernst, Jorg Pfahler, Dominik Haneberg, Wolfgang Reif
    Abstract:

    This paper gives an overview over the development of a formally verified File System for Flash memory. We describe our approach that is based on Abstract State Machines and incremental modular refinement. Some of the important intermediate levels and the features they introduce are given. We report on the verification challenges addressed so far, and point to open problems and future work. We furthermore draw preliminary conclusions on the methodology and the required tool support.

  • ABZ - Development of a Verified Flash File System
    Lecture Notes in Computer Science, 2014
    Co-Authors: Gerhard Schellhorn, Gidon Ernst, Jorg Pfahler, Dominik Haneberg, Wolfgang Reif
    Abstract:

    This paper gives an overview over the development of a formally verified File System for Flash memory. We describe our approach that is based on Abstract State Machines and incremental modular refinement. Some of the important intermediate levels and the features they introduce are given. We report on the verification challenges addressed so far, and point to open problems and future work. We furthermore draw preliminary conclusions on the methodology and the required tool support.

  • ABZ - Modular Refinement for Submachines of ASMs
    Lecture Notes in Computer Science, 2014
    Co-Authors: Gidon Ernst, Jorg Pfahler, Gerhard Schellhorn, Wolfgang Reif
    Abstract:

    We describe and formalize a compositional, contract-based submachine refinement for a variant of Abstract State Machines. We motivate the approach by models of the Flash File System case study, where it is infeasible to refine a complete machine as a whole.

Gerhard Schellhorn - One of the best experts on this subject based on the ideXlab platform.

  • VSTTE - Inside a Verified Flash File System: Transactions and Garbage Collection
    Lecture Notes in Computer Science, 2016
    Co-Authors: Gidon Ernst, Jorg Pfahler, Gerhard Schellhorn, Wolfgang Reif
    Abstract:

    The work presented here addresses a long-standing conceptual gap in Flash File System verification: We map an abstract graph-based representation down to the flat blocks of bytes of the storage medium. Specifically, we consider grouping of File System objects into atomic transactions together with layout, allocation and garbage collection of on-Flash storage space. Two major concerns guide the design and verification: proper handling of errors and, more importantly, guaranteed recovery from unexpected power cuts. Finding useful specifications of intermediate interfaces to address these concerns realistically dominates the verification effort.

  • inside a verified Flash File System transactions and garbage collection
    Verified Software: Theories Tools Experiments, 2015
    Co-Authors: Gidon Ernst, Jorg Pfahler, Gerhard Schellhorn, Wolfgang Reif
    Abstract:

    The work presented here addresses a long-standing conceptual gap in Flash File System verification: We map an abstract graph-based representation down to the flat blocks of bytes of the storage medium. Specifically, we consider grouping of File System objects into atomic transactions together with layout, allocation and garbage collection of on-Flash storage space. Two major concerns guide the design and verification: proper handling of errors and, more importantly, guaranteed recovery from unexpected power cuts. Finding useful specifications of intermediate interfaces to address these concerns realistically dominates the verification effort.

  • development of a verified Flash File System
    ABZ 2014 Proceedings of the 4th International Conference on Abstract State Machines Alloy B TLA VDM and Z - Volume 8477, 2014
    Co-Authors: Gerhard Schellhorn, Gidon Ernst, Jorg Pfahler, Dominik Haneberg, Wolfgang Reif
    Abstract:

    This paper gives an overview over the development of a formally verified File System for Flash memory. We describe our approach that is based on Abstract State Machines and incremental modular refinement. Some of the important intermediate levels and the features they introduce are given. We report on the verification challenges addressed so far, and point to open problems and future work. We furthermore draw preliminary conclusions on the methodology and the required tool support.

  • ABZ - Development of a Verified Flash File System
    Lecture Notes in Computer Science, 2014
    Co-Authors: Gerhard Schellhorn, Gidon Ernst, Jorg Pfahler, Dominik Haneberg, Wolfgang Reif
    Abstract:

    This paper gives an overview over the development of a formally verified File System for Flash memory. We describe our approach that is based on Abstract State Machines and incremental modular refinement. Some of the important intermediate levels and the features they introduce are given. We report on the verification challenges addressed so far, and point to open problems and future work. We furthermore draw preliminary conclusions on the methodology and the required tool support.

  • ABZ - Modular Refinement for Submachines of ASMs
    Lecture Notes in Computer Science, 2014
    Co-Authors: Gidon Ernst, Jorg Pfahler, Gerhard Schellhorn, Wolfgang Reif
    Abstract:

    We describe and formalize a compositional, contract-based submachine refinement for a variant of Abstract State Machines. We motivate the approach by models of the Flash File System case study, where it is infeasible to refine a complete machine as a whole.

Kyu Ho Park - One of the best experts on this subject based on the ideXlab platform.

  • high performance scalable Flash File System using virtual metadata storage with phase change ram
    IEEE Transactions on Computers, 2011
    Co-Authors: Young-woo Park, Kyu Ho Park
    Abstract:

    Several Flash File Systems have been developed based on the physical characteristics of NAND Flash memory. However, previous Flash File Systems have performance overhead and scalability problems caused by metadata management in NAND Flash memory. In this paper, we present a Flash File System called PFFS2. PFFS2 stores all metadata into virtual metadata storage, which employs Phase-change RAM (PRAM). PRAM is a next-generation nonvolatile memory and will be good for dealing with word-level read/write of small-size data. Based on the virtual metadata storage, PFFS2 can manage metadata in a virtually fixed location and through byte-level in-place updates. Therefore, the performance of PFFS2 is 38 percent better than YAFFS2 for small File read/write while matching YAFFS2 performance for large File. Virtual metadata storage is particularly effective in decreasing the burden of computational and I/O overhead of garbage collection. In addition, PFFS2 maintains a 0.18 second mounting time and 284 KB memory usage in spite of increases in NAND Flash memory size. We also propose a wear-leveling solution for PRAM in virtual metadata storage and greatly reduce the total write count of NAND Flash memory. In addition, the life span of PFFS2 is longer than other Flash File Systems.

  • NLE-FFS: a Flash File System with PRAM for non-linear editing
    IEEE Transactions on Consumer Electronics, 2009
    Co-Authors: Man-keun Seo, Young-woo Park, Kyu Ho Park
    Abstract:

    For efficient non-linear editing (NLE) operations, a Flash File System should be designed considering three factors: data indexing, System calls and frame header updates. Based on the hybrid architecture of phase-change RAM (PRAM) and NAND Flash, we introduce a non-linear editing Flash File System (NLE-FFS) which is designed for mobile multimedia devices that support NLE. In the proposed File System, the following three features are proposed. First, new data indexing scheme is proposed that is not limited by page-alignment constraint. Not only does it deal effectively with large multimedia Files, it also facilitates flexible data management. Second, new System calls are proposed that minimize re-write overhead due to NLE operations by updating a small amount of metadata. Finally, an H-data block is proposed to reduce the overhead caused by frame header updates. The H-data block is a PRAM region reserved for frame header data updates. It allows byte-level updates instead of page-level updates; hence, several bytes of frame headers can be effectively updated in this region. The experimental result of this study shows that only one second is enough for a cut operation on a five-minute video irrespective of the cutting position in NLE-FFS, whereas up to 118.7 seconds are required for the same video depending on the cutting position in YAFFS2.

  • a hybrid Flash File System based on nor and nand Flash memories for embedded devices
    IEEE Transactions on Computers, 2008
    Co-Authors: Chul Lee, Sung Hoon Baek, Kyu Ho Park
    Abstract:

    This paper presents a hybrid Flash File System (HFFS) based on both NOR Flash and NAND Flash memory. In a conventional NAND Flash-based Flash File System, there is a trade-off between life span and durability in the frequent writing of small amounts of data. Because NAND Flash supports only a page-level I/O, at least one page is wasted in the synchronous writing of small amounts of data. The wasting of pages reduces the utilization and life span of the NAND Flash. To alleviate the utilization problem, some NAND Flash-based Flash File Systems write small amounts of data asynchronously with RAM buffers, though buffering in RAM decreases the durability of the System. Our HFFS eliminates the trade-off between life span and durability. It synchronously stores data as a log in the NOR Flash, whenever we append small amounts of data to a File. The merged logs are then flushed to the NAND Flash in a page-aligned fashion. The implementation of our HFFS is based on our previous NAND Flash-based File System, called CFFS, The experimental results reveal that our HFFS provides a longer life span than a conventional NAND Flash-based synchronous Flash File System with a similar level of durability.

  • pffs a scalable Flash memory File System for the hybrid architecture of phase change ram and nand Flash
    ACM Symposium on Applied Computing, 2008
    Co-Authors: Young-woo Park, Seung-ho Lim, Chul Lee, Kyu Ho Park
    Abstract:

    In this paper, we present the scalable and efficient Flash File System using the combination of NAND and Phase-change RAM (PRAM). Until now, several Flash File Systems have been developed considering the physical characteristics of NAND Flash. However, previous Flash File Systems still have a high performance overhead and a scalability problem of the mounting time and the memory usage because, in most case, the metadata is written with several words at a single update even though the writes in NAND Flash must be performed in terms of page, which is typically 2 KiB. The proposed Flash File System called PFFS uses PRAM to mitigate the limitation of NAND Flash. The PRAM is a next generation non-volatile memory and good for dealing with word level read/write of a small size of data. PFFS hence separates the metadata from the regular data in a File System and saves them into PRAM. Consequently, the PFFS manages all the Files and directories in the PRAM and outperforms other Flash File Systems. The experimental results show that the performance of PFFS is 25% better than YAFFS2 for small-File writes while matching YAFFS2 performance for large writes and the mouting time and the memory usage of PFFS are O(1).

  • SAC - PFFS: a scalable Flash memory File System for the hybrid architecture of phase-change RAM and NAND Flash
    Proceedings of the 2008 ACM symposium on Applied computing - SAC '08, 2008
    Co-Authors: Young-woo Park, Seung-ho Lim, Chul Lee, Kyu Ho Park
    Abstract:

    In this paper, we present the scalable and efficient Flash File System using the combination of NAND and Phase-change RAM (PRAM). Until now, several Flash File Systems have been developed considering the physical characteristics of NAND Flash. However, previous Flash File Systems still have a high performance overhead and a scalability problem of the mounting time and the memory usage because, in most case, the metadata is written with several words at a single update even though the writes in NAND Flash must be performed in terms of page, which is typically 2 KiB. The proposed Flash File System called PFFS uses PRAM to mitigate the limitation of NAND Flash. The PRAM is a next generation non-volatile memory and good for dealing with word level read/write of a small size of data. PFFS hence separates the metadata from the regular data in a File System and saves them into PRAM. Consequently, the PFFS manages all the Files and directories in the PRAM and outperforms other Flash File Systems. The experimental results show that the performance of PFFS is 25% better than YAFFS2 for small-File writes while matching YAFFS2 performance for large writes and the mouting time and the memory usage of PFFS are O(1).

Jorg Pfahler - One of the best experts on this subject based on the ideXlab platform.

  • VSTTE - Inside a Verified Flash File System: Transactions and Garbage Collection
    Lecture Notes in Computer Science, 2016
    Co-Authors: Gidon Ernst, Jorg Pfahler, Gerhard Schellhorn, Wolfgang Reif
    Abstract:

    The work presented here addresses a long-standing conceptual gap in Flash File System verification: We map an abstract graph-based representation down to the flat blocks of bytes of the storage medium. Specifically, we consider grouping of File System objects into atomic transactions together with layout, allocation and garbage collection of on-Flash storage space. Two major concerns guide the design and verification: proper handling of errors and, more importantly, guaranteed recovery from unexpected power cuts. Finding useful specifications of intermediate interfaces to address these concerns realistically dominates the verification effort.

  • inside a verified Flash File System transactions and garbage collection
    Verified Software: Theories Tools Experiments, 2015
    Co-Authors: Gidon Ernst, Jorg Pfahler, Gerhard Schellhorn, Wolfgang Reif
    Abstract:

    The work presented here addresses a long-standing conceptual gap in Flash File System verification: We map an abstract graph-based representation down to the flat blocks of bytes of the storage medium. Specifically, we consider grouping of File System objects into atomic transactions together with layout, allocation and garbage collection of on-Flash storage space. Two major concerns guide the design and verification: proper handling of errors and, more importantly, guaranteed recovery from unexpected power cuts. Finding useful specifications of intermediate interfaces to address these concerns realistically dominates the verification effort.

  • development of a verified Flash File System
    ABZ 2014 Proceedings of the 4th International Conference on Abstract State Machines Alloy B TLA VDM and Z - Volume 8477, 2014
    Co-Authors: Gerhard Schellhorn, Gidon Ernst, Jorg Pfahler, Dominik Haneberg, Wolfgang Reif
    Abstract:

    This paper gives an overview over the development of a formally verified File System for Flash memory. We describe our approach that is based on Abstract State Machines and incremental modular refinement. Some of the important intermediate levels and the features they introduce are given. We report on the verification challenges addressed so far, and point to open problems and future work. We furthermore draw preliminary conclusions on the methodology and the required tool support.

  • ABZ - Development of a Verified Flash File System
    Lecture Notes in Computer Science, 2014
    Co-Authors: Gerhard Schellhorn, Gidon Ernst, Jorg Pfahler, Dominik Haneberg, Wolfgang Reif
    Abstract:

    This paper gives an overview over the development of a formally verified File System for Flash memory. We describe our approach that is based on Abstract State Machines and incremental modular refinement. Some of the important intermediate levels and the features they introduce are given. We report on the verification challenges addressed so far, and point to open problems and future work. We furthermore draw preliminary conclusions on the methodology and the required tool support.

  • ABZ - Modular Refinement for Submachines of ASMs
    Lecture Notes in Computer Science, 2014
    Co-Authors: Gidon Ernst, Jorg Pfahler, Gerhard Schellhorn, Wolfgang Reif
    Abstract:

    We describe and formalize a compositional, contract-based submachine refinement for a variant of Abstract State Machines. We motivate the approach by models of the Flash File System case study, where it is infeasible to refine a complete machine as a whole.