检索结果-南通市图书馆

维普期刊数据库

CLEC:Combination Locality Based erasure code for Permissioned Blockchain Storage

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2022年第12期73卷 5137-5150页

作者： Jiabin Wu Boai Yang Yang Liu Fang Liu Nong Xiao Shuo Li National University of Defense Technology Changsha410073China Hunan University Changsha410082China Sun Yat-sen University Guangzhou510275China The University of Edinburgh EdinburghEH89BTThe United Kingdom

Building a new decentralized domain name system based on blockchain technology is helping to solve problems,such as load imbalance and over-dependence on the trust of the central node.However,in the existing blockchain storage system,the storage overhead is very high due to its fullreplication data storage mechanism.The total storage consumption for each block is up to O(n)with n nodes.erasure code applied to blockchains can significantly reduce the storage overhead,but also greatly lower the read performance.In this study,we propose a novel coding scheme for blockchain storage,Combination Locality based erasure code for Permissioned blockchain storage(CLEC).CLEC uses erasure code,parity locality,and topology locality in blockchain storage,greatly reducing reading latency and repair time.In CLEC,the storage consumption per block can be reduced to O(1),and the repair penalty can also be lowered to O(1).Experiments in an open-source permissioned blockchain Tendermint show that CLEC has a maximum repair speed of 6 times and a read speed of nearly 1.7 times with storage overhead of only 1.17 times compared to the current work,a great improvement in reading performance and repair performance with slightly increased storage overhead via implementation.

关键词： CLEC blockchain erasure code delay circle read performance throughput repair performance

Joint video adaptation and erasure code for video broadcast in wireless networks

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2013年第10期56卷 102-116页

作者： HE NengQiang ZHANG XueDan LI YiPeng CAO JianNong LI Zhu REN Yong Department of Electronic Engineering Tsinghua University Department of Automation Tsinghua University Department of Computing Hong Kong Polytechnic University

Advances in wireless access technologies such as WiMax and LTE have accelerated the development of wireless video applications.Though existing erasure codes are designed for wireless data broadcasting,their potential can only be realized for wireless video broadcasting if the distortions associated with video packets and their complex decoding dependency are taken into consideration.In this paper,we propose the greedy video erasure code(GVEC)to minimize average video distortion by accounting for the temporal scalable decoding dependency among video frames e.g.I,P and B frames in MPEG.GVEC is a greedy algorithm and sufers from high computational complexity.For practical implementation,we have designed the joint video adaptation and erasure code(JVEC)with lower complexity,which can generate erasure codes on the fly to guarantee the decoding of important video frames.Simulation results show that the performance of JVEC is very close to that of GVEC,and is superior to that of existing erasure codes.Our results also show the existence of a performance tradeof between video distortion and video packet throughput.

关键词： wireless video broadcast erasure code video analysis

A Fault Detection Mechanism in erasure-code Byzantine Fault-Tolerance Quorum

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2006年第6期11卷 1453-1456页

作者： LIU Gang ZHOU Jingli SUN Yufen QIN Leihua College of Computer Science and Technology Huazhong University of Science and Technology Wuhan 430074 Hubei China

Fault-tolerance is increasingly significant for large-scale storage systems in which Byzantine failure of storage nodes may happen. Traditional Byzantine Quorum systems that tolerate Byzantine failures by using replication have two main limitations： low space-efficiency and static quorum variables. We propose an erasure-code Byzantine Fault-tolerance Quorum that can provide high reliability with far lower storage overhead than replication by adopting erasure code as redundancy scheme. Through read/write operations of clients and diagnose operation of supervisor, our Quorum system can detect Byzantine nodes, and dynamically adjust system size and fault threshold. Simulation results show that our method improves performance for the Quorum with relatively small quorums.

关键词： fault detection erasure code Byzantine fault-tolerance Quorum

维普期刊数据库

基于Web和erasure code的文件多云安全存储系统的设计与实现

在线全文

学校读者我要写书评

暂无评论

基于Web和Erasure Code的文件多云安全存储系统的设计与实现

作者：时薇河北科技大学

学位级别：硕士

随着大数据时代的到来,云存储以其方便快捷地对海量数据进行存储和管理的优点越来越受到企业和用户的青睐,从而得到了广泛的应用和发展。在云存储系统中,人们可以随时随地通过网络进行数据存储,但由于云端存储节点是不可控的,用户的数... 详细信息

随着大数据时代的到来,云存储以其方便快捷地对海量数据进行存储和管理的优点越来越受到企业和用户的青睐,从而得到了广泛的应用和发展。在云存储系统中,人们可以随时随地通过网络进行数据存储,但由于云端存储节点是不可控的,用户的数据可能会面临被恶意篡改或泄露的危险。越来越多的云存储数据安全事件的发生表明,云存储在为用户提供数据存储服务的同时,也为用户的数据安全造成了巨大威胁和挑战。针对云存储环境下暴露出的用户数据安全问题,为了提高云存储服务的安全性和可用性,本文提出在传统的单云存储系统的基础上引入多云存储策略。本系统利用erasure code纠删码算法对用户数据进行分块和编码,生成5个数据块,然后使用AES ECB加密算法对5个数据块进行加密,最后将加密后的5个数据块分别存储在5个不同的云存储端,从而避免了由于依赖某个云存储服务商而产生数据丢失或泄露的危险。本系统完善了现有单云存储系统存在的安全问题,提高了数据存储的安全性和可靠性。根据文件多云安全存储系统的要求,本系统实现的主要功能包括用户管理、云服务管理、Bucket管理、多云存储管理和操作日志管理。文件多云安全存储系统利用企业云存储服务提供的Java SDK,整合了5个企业云存储服务组成多云存储架构,将文件分块编码后生成的数据块经过加密后传输到5个云对象存储服务中,这不但减少了存储冗余量,还提高了系统的可靠性和数据的安全性。

关键词：多云存储 erasure code RS纠删码 AES ECB 数据安全

基于erasure code的高可用分布式存储系统的设计与实现

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

基于Erasure Code的高可用分布式存储系统的设计与实现

作者：肖哲锋国防科学技术大学

学位级别：硕士

自“9?11”事件之后,数据存储日益受到重视,如何确保数据的安全性成为人们关注的焦点,这要求具有安全可靠的分布式数据存储系统的出现,它将信息分散在网络或数个存储节点上,使用户在持续有效且高度可靠的方式下访问信息,即使系统在节点... 详细信息

自“9?11”事件之后,数据存储日益受到重视,如何确保数据的安全性成为人们关注的焦点,这要求具有安全可靠的分布式数据存储系统的出现,它将信息分散在网络或数个存储节点上,使用户在持续有效且高度可靠的方式下访问信息,即使系统在节点失效,网络断开,或受到恶意攻击的情况下,仍能有效的提供数据存储服务。分布式散列表技术DHT的引入,使得基于P2P的广域存储系统的研究成为当今的热点,在研的系统包括:OceanStore(Berkeley)、CFS(MIT)、Past(Rice&Microsoft)、Granary(清华大学)等。但由于实际P2P环境中的异构性,动态性,不可信任性及易受攻击性,影响了存储系统的可用性。本文在863项目“协作式应急响应服务与基于漂移的可生存系统研究”的基础上,将erasure code与DHT结合起来,研究高可用的分布式存储系统的设计与实现,主要工作包括以下方面: 1)分析了P2P技术在分布式存储系统研究方面的优势,对分布式存储系统的研究现状做了总结和归纳,并且研究了P2P技术的相关理论;2)分析、实现了基于Vandermonde矩阵与基于Cauchy矩阵的erasure code算法,并对两种算法进行了对比测试,结果表明基于Cauchy矩阵的算法较之基于Vandermonde矩阵的算法编解码效率分别提高了43%和76%;3)提出一种基于erasure code技术的高可用分布式存储系统的体系结构,详细设计了系统的各个关键模块:文件编解码模块、分块分发与获取模块、动态维护模块、其它功能模块,并进行了性能分析;4)实现了基于erasure code技术的高可用分布式存储系统原型HHStore。对系统的性能测试表明,集中式服务器的下载方式在节点数激增时,节点下载所用的时间也增加非常迅速,其性能下降也非常快,而HHStore在网络规模非常大时,也能保持良好的性能。通过以上工作,本文设计并且实现了高可用的分布式存储系统,该系统能安全可靠地实现数据的存储与下载,能满足国防等关键部门涉密数据的分布存储要求,同时能够适应广域网中海量节点的并发下载请求,具有较好的可用性、安全性和易管理性,具有一定的军事及民用价值。

关键词： erasure code P2P 冗余高可用性存储系统分布式

基于erasure code编码机制的云平台建模与分析

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

基于Erasure Code编码机制的云平台建模与分析

作者：邹星舜山东大学

学位级别：硕士

近年来大数据与云存储的技术日益成熟,并被广泛使用于各种学术以及商用领域。各种各样的小型机存储服务器开始将存储信息迁移至云平台。云平台数据存储的可靠性,安全性,以及性能开始被越来越多的研究者关注。研究表明,对比使用传统方式... 详细信息

近年来大数据与云存储的技术日益成熟,并被广泛使用于各种学术以及商用领域。各种各样的小型机存储服务器开始将存储信息迁移至云平台。云平台数据存储的可靠性,安全性,以及性能开始被越来越多的研究者关注。研究表明,对比使用传统方式在云平台中存储文件,使用erasure code(EC)编码作为云平台的存储方式可以极大地提高云平台的存储利用率与可靠性。由于EC编码的引入,导致针对于传统策略“每个文件在不同服务器节点存储多份副本”的评估模型不再适用。在缺乏理论模型的情况下,对使用EC编码的云平台进行系统设计、分析与性能评估等都变得难以实现或者精准度欠佳。本文研究了一种准确的云平台理论分析模型,可以极大地改变这种情况,无论是对云平台的设计还是性能预测这一模型都具有重要的应用价值。本文将排队论模型应用于EC编码云平台的服务器节点建模,从而评估云平台文件请求时间上界。对云平台中服务器节点建模时,研究者们大多采用了泊松到达/服务过程的单服务器有限队列模型,即M/M/1/K排队模型。该模型认为服务器节点上文件请求的到达方式为泊松到达,每个节点处理请求的过程也是串行处理的。然而在实际过程中,文件请求的批量到达与服务器节点的并行处理是存在的。经验化地使用M/M/1/K或者M/G/1排队模型并不能对云平台系统进行准确的分析和描述。因此,本文提出了使用批量到达/服务过程(MGeo)单服务器模型对服务器节点建模。并基于已有的队列模型MGeo/MGeo/1队长分布的闭合表达式,推导出该模型与MGeo/M/1顾客等待时间的一阶矩和二阶矩的闭合形式表达式。此外,经过实验数据的统计,发现使用泊松过程对仅具有串行服务能力节点的服务过程进行建模并不准确,移位泊松过程sM相对于传统模型更能精准地刻画服务器节点的服务过程。通过考虑在每一批顾客到达之前和到达之后的瞬间嵌入相互依赖的两个马尔科夫过程,得到MGeo/sM/1队长分布的z变换,以及顾客等待时间的一阶矩与二阶矩的闭合形式表达式。综上所述,本文提出一个严格的云平台文件请求延迟的上界,用于在EC编码的云平台中预测文件请求延迟。其理论上界通过与仿真实验部分以及使用M/G/1排队模型建模的上界相比,在云平台系统处于不同负载之下,其上界依然保持与真实实验值的微小误差。该排队模型与上界在对于云平台系统的评估与预测等方面都有研究意义和应用价值。

关键词：性能建模云存储分布式系统 erasure code 排队论延迟边界

Scalable local reconstruction code design for hot data reads in cloud storage systems

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2022年第12期65卷 284-300页

作者： Zhikai ZHANG Shushi GU Qinyu ZHANG School of Electronic and Information Engineering Harbin Institute of Technology (Shenzhen) Peng Cheng Laboratory

Since demand for data is significantly heterogeneous in cloud storage systems(CSSs), there is traffic congestion in nodes storing hot data. In erasure-coded CSSs, traffic congestion can be alleviated by degraded reads sacrificing the bandwidth of surviving nodes. Local reconstruction codes(LRCs) reduce the bandwidth consumption of degraded reads, but cannot provide skewed throughput gain for the hot data. In this paper, we propose a scalable local reconstruction code(SLRC) that relies on LRCs but is more flexible in improving the throughput of a specific data block. First, we develop the local maximum throughput(LMT) to measure the maximum throughput of the hot data blocks by analyzing the actual read arrival rate of LRCs. Further, we elaborate on the structure of SLRC and analyze their performance metrics, which include storage overhead, reconstruction cost, and LMT. To select the appropriate code, we present the minimum reconstruction cost, minimum storage overhead, and minimum penalty algorithms. Finally, we implement extensive experiments on several typical SLRCs on the Hadoop distributed file system. Higher LMT and lower bandwidth consumption can be provided by SLRCs for hot data block degraded reads in CSSs compared with RS codes and LRCs.

关键词： cloud storage systems erasure code scalable local reconstruction code degraded reads local maximum throughput

DDUC:an erasure-coded system with decoupled data updating and coding

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Information Technology & Electronic Engineering 2023年第5期24卷 716-730页

作者： Yaofeng TU Rong XIAO Yinjun HAN Zhenghua CHEN Hao JIN Xuecheng QI Xinyuan SUN State Key Laboratory of Mobile Network and Mobile Multimedia Technology Shenzhen 518000China ZTE Corporation Nanjing 210000China

In distributed storage systems,replication and erasure code(EC)are common methods for data redundancy.Compared with replication,EC has better storage efficiency,but suffers higher overhead in update.Moreover,consistency and reliability problems caused by concurrent updates bring new challenges to applications of EC.Many works focus on optimizing the EC solution,including algorithm optimization,novel data update method,and so on,but lack the solutions for consistency and reliability problems.In this paper,we introduce a storage system that decouples data updating and EC encoding,namely,decoupled data updating and coding(DDUC),and propose a data placement policy that combines replication and parity blocks.For the(N,M)EC system,the data are placed as N groups of M+1 replicas,and redundant data blocks of the same stripe are placed in the parity nodes,so that the parity nodes can autonomously perform local EC encoding.Based on the above policy,a two-phase data update method is implemented in which data are updated in replica mode in phase 1,and the EC encoding is done independently by parity nodes in phase 2.This solves the problem of data reliability degradation caused by concurrent updates while ensuring high concurrency performance.It also uses persistent memory(PMem)hardware features of the byte addressing and eight-byte atomic write to implement a lightweight logging mechanism that improves performance while ensuring data consistency.Experimental results show that the concurrent access performance of the proposed storage system is 1.70–3.73 times that of the state-of-the-art storage system Ceph,and the latency is only 3.4%–5.9%that of Ceph.

关键词： Concurrent update High reliability erasure code Consistency Distributed storage system

维普期刊数据库

AVirtual Cloud Storage Architecture for Enhanced Data Security

在线全文

学校读者我要写书评

暂无评论

Computer Systems Science & Engineering 2023年第2期44卷 1735-1747页

作者： M.Antony Joans Kumar C.Christopher Columbus E.Ben George T.Ajith Bosco Raj Department of Information Technology St.Xavier’s Catholic College of EngineeringNagercoil629003Tamil NaduIndia Department of Computer Science Engineering PSN College of Engineering and TechnologyTirunelveli627152India Department of Computer Science Engineering University of Technology and Applied SciencesMuscat112Oman Department of Electronics and Communications Engineering PSN College of Engineering and TechnologyTirunelveli627152India

The sensitive data stored in the public cloud by privileged users,such as corporate companies and government agencies are highly vulnerable in the hands of cloud providers and hackers.The proposed Virtual Cloud Storage Archi-tecture is primarily concerned with data integrity and conﬁdentiality,as well as availability.To provide conﬁdentiality and availability,theﬁle to be stored in cloud storage should be encrypted using an auto-generated key and then encoded into distinct chunks.Hashing the encoded chunks ensured theﬁle integrity,and a newly proposed Circular Shift Chunk Allocation technique was used to determine the order of chunk storage.Theﬁle could be retrieved by performing the opera-tions in reverse.Using the regenerating code,the model could regenerate the missing and corrupted chunks from the cloud.The proposed architecture adds an extra layer of security while maintaining a reasonable response time and sto-rage capacity.Experimental results analysis show that the proposed model has been tested with storage space and response time for storage and retrieval.The VCSA model consumes 1.5x(150%)storage space.It was found that total storage required for the VCSA model is very low when compared with 2x Replication and completely satisﬁes the CIA model.The response time VCSA model was tested with different sizedﬁles starting from 2 to 16 MB.The response time for storing and retrieving a 2 MBﬁle is 4.96 and 3.77 s respectively,and for a 16 MBﬁle,the response times are 11.06 s for storage and 5.6 s for retrieval.

关键词： erasure code regenerating code cryptography virtual cloud storage architecture circular shift chunk allocation algorithm