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file SYSTEM CACHING IN LARGE POINT-TO-POINT NETWORKS

SOFTWARE ENGINEERING JOURNAL 1992年第1期7卷 65-80页

作者： AUSTIN, PB MURRAY, KA WELLINGS, AJ UNIV YORK DEPT COMP SCIYORK YO1 5DDN YORKSHIREENGLAND

In this paper, we examine the design of a file system for a general-purpose scalable parallel computing engine, based on an extensible mesh of processors. Although many distributed file systems have already been developed, none have properly addressed the characteristics that are special to these computing engines, namely dynamic load-balancing and point-to-point networks. Client caching is identified as a key area where current systems fall short. We propose two new caching schemes that employ an extra level of caching in addition to that used by current client caching schemes. We present some results from a simulation study of the two new caching schemes, which demonstrate that the schemes outperform traditional client caching schemes when used in a general-purpose processor mesh-based, parallel computing engine. Since one of these caching schemes is quite complex, we have developed a formal specification in the Z language.

关键词： formal specification Z language Software engineering techniques parallel machines buffer storage general-purpose processor mesh-based Parallel architecture simulation study client caching schemes Multiprocessing systems point-to-point networks distributed file systems Parallel programming parallel architectures file organisation file organisation general-purpose scalable parallel computing engine dynamic load-balancing extensible mesh

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A quorum-based protocol for searching objects in peer-to-peer networks

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IEEE TRANSACTIONS ON PARALLEL AND distributed systems 2006年第1期17卷 25-37页

作者： Miura, K Tagawa, T Kakugawa, H Oki Data Corp Minato Ku Tokyo 1088551 Japan Hiroshima Univ Dept Informat Engn Hiroshima 7398527 Japan Osaka Univ Grad Sch Informat Sci & Technol Dept Comp Sci Osaka 5608531 Japan

Peer-to-peer (P2P) system is an overlay network of peer computers without centralized servers, and many applications have been developed for such networks such as file sharing systems. Because a set of peers dynamically changes, design and verification of efficient protocols is a challenging task. In this paper, we consider an object searching problem under a resource model such that there are some replicas in a system and the lower bound of the ratio rho = n'/n is known in advance, where n' is a lower bound of the number of peers that hold original or replica for any object type and n is the total number of peers. In addition, we consider object searching with probabilistic success, i.e., for each object search, object must be found with at least probability 0 < sigma < 1. To solve such a problem efficiently, we propose a new communication structure, named probabilistic weak quorum systems (PWQS), which is an extension of coterie. Then, we propose a fault-tolerant protocol for searching for objects in a P2P system. In our method, each peer does not maintain global information such as the set of all peers and a logical topology with global consistency. In our protocol, each peer communicates only a small part of a peer set and, thus, our protocol is adaptive for huge scale P2P network.

关键词： distributed systems distributed data structures reliability and robustness combinatorial algorithms distributed file systems

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Prefetching on Storage Servers through Mining Access Patterns on Blocks

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IEEE TRANSACTIONS ON PARALLEL AND distributed systems 2016年第9期27卷 2698-2710页

作者： Liao, Jianwei Trahay, Francois Gerofi, Balazs Ishikawa, Yutaka Southwest Univ China Coll Comp & Informat Sci Chongqing 400715 Peoples R China Nanjing Univ State Key Lab Novel Software Technol Nanjing 210023 Jiangsu Peoples R China Telecom SudParis Paris France RIKEN Adv Inst Computat Sci Kobe Hyogo Japan Univ Tokyo Tokyo 1138654 Japan

distributed file systems have been widely deployed as back-end storage systems to offer I/O services for parallel/distributed applications that process large amounts of data. Data prefetching in distributed file systems is a well-known optimization technique which can mask both network and disk latency and consequently boost I/O performance. Traditionally, data prefetching is initiated by the client file systems, however, conventional prefetching schemes are not well suited for client machines that have limited memory and computing capacity. To offer an efficient prefetching approach for resource-limited client machines, this paper proposes a novel server-side prefetching mechanism. Specifically, we propose to piggyback client identification to I/O requests so that server side block access history can be put into context. On the server side, we utilize the horizontal visibility graph technique to transform perclient time series of block access sequences into a connected graph for which we employ Tarjan's algorithm to disclose cut points in the connected graph. We express these patterns with feature tuples and we propose the X-step pattern matching algorithm to find a matching access pattern (i.e., a feature tuple) for a given block access history. Experimental results indicate that our newly proposed prefetching mechanism can ease client machines and their applications from the process of data prefetching, boosting client performance accordingly, and that it yields an attractive increase in data throughput as well.

关键词： Storage servers distributed file systems data prefetching block access patterns horizontal visibility graph

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NFS-CD: Write-enabled cooperative caching in NFS

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IEEE TRANSACTIONS ON PARALLEL AND distributed systems 2008年第3期19卷 323-333页

作者： Batsakis, Alexandros Burns, Randal Johns Hopkins Univ Dept Comp Sci Baltimore MD 21218 USA

We present the Network file System with Cluster Delegation (NFS-CD), an enhancement to the NFSv4 that reduces server load and increases the scalability of distributed file systems in computing clusters. The cluster delegation feature of NFS-CD allows data sharing among clients by extending the NFSv4 delegation model so that multiple clients manage a single file without interacting with the server. Based on cluster delegation, we implement a fast-commit primitive, cooperative caching, and the ability to recover the uncommitted updates of a failed computer. NFS-CD supports both read and write operations in the cooperative cache without degrading the consistency model of NFSv4. We have implemented NFS-CD by modifying the Linux NFSv4 client only. Because the server remains unchanged, NFS-CD preserves the simple administration model of NFSv4 and interoperates with standard NFS clients. NFS-CD offers improved performance when compared to NFSv4 at the expense of slightly weaker reliability guarantees. An experimental evaluation of our implementation, using industry standard benchmarks and application workloads, reveals that NFS-CD reduces server load by more than half. It also demonstrates that under most workloads, file systems must support writes to the cooperative cache to achieve scale.

关键词： distributed systems distributed file systems data structures data

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Decentralized Attestation and Distribution of Information Using Blockchains and Multi-Protocol Storage

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IEEE ACCESS 2022年 10卷 18035-18054页

作者： Harer, Felix Fill, Hans-Georg Univ Fribourg Dept Informat Digitalizat & Informat Syst Grp CH-1700 Fribourg Switzerland

The distribution of information through web protocols is today based on the client-server model. Recently, decentralized protocols with greater availability appear as well as blockchain-based attestation methods, allowing for proving the existence of information. In combination, these methods promise a secure, decentralized and long-term storage. However, there exist two major problems: (1) the scalability of blockchains limits their storage capacity and (2) various (de)centralized web protocols are in use and could alleviate this problem, but they do not support blockchain-based attestations. In this paper, we extend an approach for blockchain-based attestation with compatibility for multi-protocol storage. Instead of specific protocols or blockchains, the extended approach aims to contribute novel concepts to the discussion on blockchain scalability. It augments the capabilities of existing protocols for applications such as certification or timestamping of digital artifacts. With the use of decentralized protocols such as IPFS, further availability and inherent resilience properties are gained, allowing for applications such as open research repositories and digital registries. We discuss the architecture of the extended approach, a possible implementation in a smart contract on the Ethereum blockchain with IPFS and Git, and evaluate the time and cost of attestations.

关键词： Protocols Blockchains Servers Metadata Computer architecture Data integrity Software Blockchain distributed information systems decentralized identifiers distributed file systems internet protocols

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Mobile information access

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IEEE PERSONAL COMMUNICATIONS 1996年第1期3卷 26-33页

作者： Satyanarayanan, M School of Computer Science Carnegie Mellon University

The ability to access information on demand when mobile will be a critical capability in the 21st century. In this paper, we examine the fundamental forces at work in mobile computing systems and explain how they constrain the problem of mobile information access. From these constraints, we derive the importance of adaptivity as a crucial requirement of mobile clients. We then develop a taxonomy of adaptation strategies, and summarize our research in application-transparent and application-aware adaptation in the Coda and Odyssey systems respectively.

关键词： Mobile computing Databases adaptivity application-transparent adaptation application-aware adaptation laissez-faire strategies distributed file systems multimedia data weak connectivity intermittence low-bandwidth networks Coda Odyssey disco

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PROCESS DATA INFRASTRUCTURE AND DATA SERVICES

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COMPUTING AND INFORMATICS 2020年第4期39卷 724-756页

作者： Cushing, Reginald Valkering, Onno Belloum, Adam Madougou, Souley Bobak, Martin Habala, Ondrej Tran, Viet Meizner, Jan Nowakowski, Piotr Graziani, Mara Mueller, Henning Univ Amsterdam Inst Informat Amsterdam Netherlands Netherlands eSci Ctr Sci Pk 140 NL-1098 XG Amsterdam Netherlands Slovak Acad Sci Inst Informat Dubravska Cesta 9 Bratislava 84507 Slovakia AGH Univ Sci & Technol Krakow UCC Cyfronet AGH Krakow Poland Univ Appl Sci Western Switzerland HES SO Valais CH-3960 Sierre Switzerland Univ Geneva Dept Comp Sci CH-1227 Carouge Switzerland

Due to energy limitation and high operational costs, it is likely that exascale computing will not be achieved by one or two datacentres but will require many more. A simple calculation, which aggregates the computation power of the 2017 Top500 supercomputers, can only reach 418 petaflops. Companies like Rescale, which claims 1.4 exaflops of peak computing power, describes its infrastructure as composed of 8 million servers spread across 30 datacentres. Any proposed solution to address exascale computing challenges has to take into consideration these facts and by design should aim to support the use of geographically distributed and likely independent datacentres. It should also consider, whenever possible, the co-allocation of the storage with the computation as it would take 3 years to transfer 1 exabyte on a dedicated 100 Gb Ethernet connection. This means we have to be smart about managing data more and more geographically dispersed and spread across different administrative domains. As the natural settings of the PROCESS project is to operate within the European Research Infrastructure and serve the European research communities facing exascale challenges, it is important that PROCESS architecture and solutions are well positioned within the European computing and data management landscape namely PRACE, EGI, and EUDAT. In this paper we propose a scalable and programmable data infrastructure that is easy to deploy and can be tuned to support various data-intensive scientific applications.

关键词： Exascale data management distributed file systems microservice architecture

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Crocus: Enabling Computing Resource Orchestration for Inline Cluster-Wide Deduplication on Scalable Storage systems

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IEEE TRANSACTIONS ON PARALLEL AND distributed systems 2020年第8期31卷 1740-1753页

作者： Hamandawana, Prince Khan, Awais Lee, Chang-Gyu Park, Sungyong Kim, Youngjae Ajou Univ Dept Comp Engn Suwon 16499 South Korea Sogang Univ Dept Comp Sci & Engn Seoul 04107 South Korea

Inline deduplication dramatically improves storage space utilization. However, it degrades I/O throughput due to compute-intensive deduplication operations such as chunking, fingerprinting or hashing of chunk content, and redundant lookup I/Os over the network in the I/O path. In particular, the fingerprint or hash generation of content contributes largely to the degraded I/O throughput and is computationally expensive. In this article, we propose Crocus, a framework that enables compute resource orchestration to enhance cluster-wide deduplication performance. In particular, Crocus takes into account all compute resources such as local and remote {CPU, GPU} by managing decentralized compute pools. An opportunistic Load-Aware Fingerprint Scheduler (LAFS), distributes and offloads compute-intensive deduplication operations in a load-aware fashion to compute pools. Crocus is highly generic and can be adopted in both inline and offline deduplication with different storage tier configurations. We implemented Crocus in Ceph scale-out storage system. Our extensive evaluation shows that Crocus reduces the fingerprinting overhead by 86 percent with 4KB chunk size compared to Ceph with baseline deduplication while maintaining high disk-space savings. Our proposed LAFS scheduler, when tested in different internal and external contention scenarios also showed 54 percent improvement over a fixed or static scheduling approach.

关键词： distributed file systems scheduling storage management

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Pervasive Tabs, Pads, and Boards: Are We There Yet?

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IEEE PERVASIVE COMPUTING 2012年第1期11卷 42-50页

作者： Ebling, Maria R. Baker, Mary IBM TJ Watson Res Ctr Yorktown Hts NY USA

How far have we come with respect to commercial deployments of the devices Mark Weiser described? This review of Weiser's vision evaluates the commercial success of tabs, pads, and boards and discusses their real-... 详细信息

关键词： Medicine And Science Health Privacy Support For Adaptation distributed file systems Introductory And Survey Mobile Environments distributed systems

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Moving metadata from ad hoc files to database tables for robust, highly available, and scalable HDFS

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JOURNAL OF SUPERCOMPUTING 2017年第6期73卷 2657-2681页

作者： Won, Heesun Minh Chau Nguyen Gil, Myeong-Seon Moon, Yang-Sae Whang, Kyu-Young Korea Adv Inst Sci & Technol Sch Comp Daejeon South Korea ETRI BigData Intelligence Res Dept Daejeon South Korea Kangwon Natl Univ Dept Comp Sci Chunchon South Korea

As a representative large-scale data management technology, Apache Hadoop is an open-source framework for processing a variety of data such as SNS, medical, weather, and IoT data. Hadoop largely consists of HDFS, MapReduce, and YARN. Among them, we focus on improving the HDFS metadata management scheme responsible for storing and managing big data. We note that the current HDFS incurs many problems in system utilization due to its file-based metadata management. To solve these problems, we propose a novel metadata management scheme based on RDBMS for improving the functional aspects of HDFS. Through analysis of the latest HDFS, we first present five problems caused by its metadata management and derive three requirements of robustness, availability, and scalability for resolving these problems. We then design an overall architecture of the advanced HDFS, A-HDFS, which satisfies these requirements. In particular, we define functional modules according to HDFS operations and also present the detailed design strategy for adding or modifying the individual components in the corresponding modules. Finally, through implementation of the proposed A-HDFS, we validate its correctness by experimental evaluation and also show that A-HDFS satisfies all the requirements. The proposed A-HDFS significantly enhances the HDFS metadata management scheme and, as a result, ensures that the entire system improves its stability, availability, and scalability. Thus, we can exploit the improved distributed file system based on A-HDFS for various fields and, in addition, we can expect more applications to be actively developed.

关键词： Hadoop HDFS Advanced HDFS distributed file systems Metadata management

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