A storage structure definition language for Codasyl Data Bases

This paper proposes a language for the definition of the physical storage structures in a Codasyl Data Base.The language is based on the idea of using a generalized model of the storage structures, called Virtual Paged Memory, which is capable of expressing many of the features which characterize the storage structures of many existing systems. This model is used as an intermediate level between the DDL-schema and the physical database.A critical comparison between the proposed approach and the BCS/CODASYL DDLC DBWAG proposal for a tentative standard of a storage schema definition language is also presented.     

Storage administrators: emerging IT specialty

Companies are generating data at a faster rate than ever before because of many factors, including the exponential growth of applications and Web generated contents. This has led to significant increases in storage requirements and a larger percentage of IT budgets being allocated for storage purchases. Storage specialists can play a decisive role in ensuring the company never faces the specter of losing critical data.     

Portable electronic storage systems

Notebook, palmtop, and pen-based computers have unique storage requirements. In addition to a rapid growth in capacity to support emerging multimedia applications, portable systems require small, removable media; high shock resistance; thermal resilience; and light-weight, unique form factors dictated by ergonomic constraints and choices. It is argued that storage is the critical enabling technology for many new multimedia applications and addressing its rapidly increasing requirements is key to bringing forward this new technology     

Toward practical guideline for design of image compression algorithms for biomedical applications

Improvements in medicine and healthcare are accelerating. Information generation, sharing, and expert analysis, play a great role in improving medical sciences. Big data produced by medical procedures in hospitals, laboratories, and research centers needs storage and transmission. Data compression is a critical tool that reduces the burden of storage and transmission. Medical images, in particular, require special consideration in terms of storage and transmissions. Unlike many other types of big data, medical images require lossless storage. Special purpose compression algorithms and codecs could compress variety of such images with superior performance compared to the general purpose lossless algorithms. For the medical images, many lossless algorithms have been proposed so far. A compression algorithm comprises of different stages. Before designing a special purpose compression method we need to know how much each stage contributes to the overall compression performance so we could accordingly invest time and effort in designing different stages. In order to compare and evaluate these multi-stage compression techniques and to design more efficient compression methods for big data applications, in this paper the effectiveness of each of these compression stages on the total performance of the algorithm is analyzed.     

Deductive Fault Simulation Algorithm Based on Fault Collapsing

The true value simulation is necessary in the critical path tracing fault simulation algorithm.The critical and non-critical inputs can be known after the number of controlling and non-controlling inputs and the criticality of output of every gate are determined.Single output region(SOR)is defined for non-critical lines,so many other non-critical lines can be obtained before fault simulation.The deductive fault simulation algorithm is used to compute the fault list for every possible critical line from bottom to top,which can greatly decrease the length of fault list and simulation time.The cross-sectios is defined to reduce the storage space.The experimental results are given at the end of the paper.     

A power-saving data storage scheme for wireless sensor networks

In wireless sensor network (WSN), sensors are small, inexpensive, and computable. However, they are limited in power, memory, and computational capacities. A large number of tiny sensors are usually deployed randomly to monitor one or more phenomena to collect and process the sensed data, and to send the data back to the sink. Many literatures focus on developing power-saving protocols. In addition, many papers present data storage schemes but they do not take power saving into consideration. Hence, these data storage schemes cannot perform well based on power-saving protocols. Therefore, it is very critical to propose a data storage scheme to support power-saving mechanism. In this paper, we propose a power-saving data storage scheme for WSN. Our scheme adopts grid-based architecture, in which each grid guarantees that two sensors will stay in active mode while the others stay in sleep mode to save energy. Simulation results show that our power-saving data storage scheme can reduce energy consumption.     

IPTV建设中的两个关键技术问题及其解决方案

针对IPTV系统的试点建设中,遇到的诸多直接关系到用户体验质量、组网成本以及规模应用等技术问题,在对其中的两个关键问题———节点存储问题和直播业务的QOS问题进行探索的基础上,通过对几种常见的CDN节点存储方案所进行的性能与成本分析对比,得出了SAN方案是最佳选择的结论。随后,对影响直播业务QOS的两个关键问题———频道切换和组播丢包问题进行了深入的分析,并据此提出了切实可行的解决方案。     

公有云存储系统性能评测方法研究

随着云存储系统的迅速发展和广泛使用,许多企业开发者和个人用户将其应用从传统存储迁移至公有云存储系统,因此,云存储系统性能成为企业开发者和个人用户关注的焦点。由于传统测试难以模拟足够多的用户同时访问云存储系统;测试环境构建复杂,测试时间长,准备测试环境成本高;受网络因素及外界其他因素影响,评测结果不稳定。针对以上所述云存储系统性能评测的重点和难点,提出一种“云测试云”的公有云存储系统性能评测方法,该方法通过在云计算平台动态申请足够数量的实例,对公有云存储系统性能进行评测。首先,构建通用的性能评测框架,可动态伸缩申请实例,自动化部署评测工具及负载,控制并发访问云存储系统,自动释放实例及收集并反馈评测结果;其次,提出多维度的性能评测指标,涵盖不同典型应用、不同云存储接口;最后,提出一种可扩展通用的性能评测模型,该模型可以评测常见典型应用的性能,分析云存储性能影响因素,可适用于任何的公有云存储平台。为了验证该方法的可行性、合理性、通用性和可扩展性,利用所提方法对Amazon S3云存储系统进行性能评测,并使用s3cmd验证评测结果的准确性。实验结果表明,评测结果可以为企业开发者和个人用户提供参考意见。     

基于VC++的金属充氚系统实时监控软件设计

介绍了以Visual C++为开发工具,以PC机为上位机,通过串口与现场仪表通信的金属充氚自动控制系统,该系统使用了MoxaPComm Lite2.5的API函数、多线程技术、定时器、Windows等待函数、同步事件对象、临界区对象等技术来实现多串口的通信。分析论述了监控软件实时数据的采集、储存,数据曲线的绘制,温度信号控制等功能的实现方法。     

Hard drive technology reaches a turning point

Hard-drive technology is at a critical point in its history. Vendors are hitting limits on the amount of data that current technology can read and write on a square inch of disk space. While hard drive capacity will continue to increase, the rate of areal-density growth will likely slow. This will hurt companies such as Maxtor, that make much of their revenue by selling new and bigger hard drives on an ongoing basis. Moreover, hard drive prices per gigabyte of storage capacity have fallen because of industry advances, thereby reducing many vendors' profit margins. For this reason, researchers are developing new approaches that could increase storage density and capacity. The most important forces driving future hard drive demand will be home entertainment devices, although products such as camcorders, cameras, and PDAs will also play an important role.     

A New Storage Scheme for Approximate Location Queries in Object-Tracking Sensor Networks

Energy efficiency is one of the most critical issues in the design of wireless sensor networks. Observing that many sensor applications for object tracking can tolerate a certain degree of imprecision in the location data of tracked objects, this paper studies precision-constrained approximate queries that trade answer precision for energy efficiency. We develop an energy-conserving approximate storage (EASE) scheme to efficiently answer approximate location queries by keeping error-bounded imprecise location data at some designated storage node. The data impreciseness is captured by a system parameter called the approximation radius. We derive the optimal setting of the approximation radius for our storage scheme based on the mobility pattern and devise an adaptive algorithm to adjust the setting when the mobility pattern is not available a priori or is dynamically changing. Simulation experiments are conducted to validate our theoretical analysis of the optimal approximation setting. The simulation results show that the proposed EASE scheme reduces the network traffic from a conventional approach by up to 96 percent and, in most cases, prolongs the network lifetime by a factor of 2-5.     

一种保护云存储平台上用户数据私密性的方法

近年来,云存储被研究者和IT厂商广泛关注,许多应用程序都用云存储来存储数据.但是用户和厂商都对于云存储的安全性和私密性问题表示忧虑.云存储安全的核心是分布式文件系统的安全性和私密性.基于SSL安全连接和Daoli安全虚拟监控系统可以充分保护分布式文件系统中用户数据的安全性和私密性.安全虚拟监督系统可以阻止传统攻击及来自云管理员的攻击.针对用户的不同需求和数据存储系统的特点,有2种解决方案,分别针对分布式文件系统中用户文件的每一块进行保护,保障用户文件每一块的私密性及对整个用户文件进行保护,保证用户文件整体私密性.对于用户数据的私密性而言,SSL安全连接和虚拟监控系统引入的性能损失是可以被接受的.     

视频网格服务器存储容量模型研究

针对基于内容分发网络(CDN)技术的视频网格中中心与区域服务器存储系统的不同职能,分析了在不同影片数量规模和分布特征情况下,随着区域服务器相对存储容量的增加,本地服务率上升的规律,在本地服务率增长的临界点附近得出了较为经济的、以中心服务器存储容量为基准的区域服务器的相对存储容量,该容量兼顾了区域服务器本地服务率和存储系统的硬件投资,能够为实际视频网格的建设提供参考。     

基于Ethernet多节点网络存储系统的研究

Internet的发展,要求一些计算机服务能够提供不间断的数据访问服务。传统的第二级存储设备的特点决定了它不适合于实现不间断数据访问。现有的解决方法如:SAN和NAS等,往往代价高昂。利用网络软RAID技术,基于Ethernet实现的网络存储器,具有第二级存储设备的性质和网络存储的优点,单位存储成本低,而且可以执行第三级存储器的数据备份功能,可以较好地满足对性能和价格的要求。     

基于可信级别的多级安全策略及其状态机模型

虽然MLS(multilevel security)被广泛应用于各种安全系统,但是它不能实现信道控制等重要的安全策略.将可信级别的概念引入到MLS中,使其可以方便地实现各种信道控制策略.建立了一个实现这种基于可信级别的多级安全策略的访问控制状态机模型,并证明其对定义的策略是安全的,而且可以实现所有静态信息流策略.另外,还扩展了该模型,使其可以支持存储对象安全属性的动态改变.该模型克服了MLS不能解决安全降级问题以及不考虑完整性的缺点,同时又保留了传统分级策略模型易理解、易使用的优点.     

一种面向大规模存储系统的数据副本映射算法

提出一种适应动态环境、无需数据映射表的多副本数据对象映射算法.该算法引入节点权重,借鉴一致性Hash技术,使得海量的数据对象按照节点服务能力在各存储节点间均匀分布;当存储节点个数发生变化时,数据依然在节点间均匀分布,且数据迁移量接近理论下限;只需维护少量数据即可计算得到数据布局,从而有效提高了系统的可扩展性.测试结果表明,算法可使所有节点分配对象个数与理论值偏差小于5%,节点个数变化时移动数据数量与理论下限偏差小于1%.     

高效的部分冗余容错编译:复制错误流关键子图

传统的容错编译通常复制所有的计算并且使用完全冗余的存储单元来保证容错.这种完全冗余在存储空间和性能上的开销都是相当大的.在错误流分析的基础上提出错误流图的关键子图的概念以及通过关键结点和关键路径生成关键子图的方法,并设计了通过复制错误流关键子图实现部分冗余的算法.在保证有效容错能力的同时,部分冗余明显减小了经过容错编译的程序在存储空间和性能上的开销.实验显示,与复制全部错误流图的完全冗余相比,在结点覆盖率降低6.25%的情况下,部分冗余算法最多能够减少寄存器的使用数量6.25%,减少功耗超过17%,减少执行时间接近26%,同时提高性能超过22%.     

一种基于云环境的文件存储策略的研究

云存储是云计算技术的重要组成部分,包括存储位置的选择和文件的传输,文件传输环节包括上传和下载。传输作为存储的重要组成部分,对于存储效率有较大的的影响。近年来针对云存储技术的研究主要集中在数据存储和数据传输的效率上,针对大量流媒体文件上传至云存储服务器过程中传输效率低的问题,在私有云环境下提出了一种针对大量流媒体文件的传输机制THU,在该机制中提出了一种对于不同的云平台环境和传输客户端存在文件大小值fk的思路,将小于该值的文件无损打包成一定数量的大小为fk的文件进行传输,而将大于fk值的文件切割成一定数量大小为fk的文件进行传输,相比较打包或者切割成其他大小的文件进行传输时消耗的时间较少。本文在私有云环境下进行了大量的流媒体ftp传输实验,实验结果显示这样的fk值是存在的,当文件打包大小或等于该值时,打包、解包和传输消耗的总时间处于相对优化的水平,从而证明了THU机制的正确性和有效性。     

Multimedia Caching Strategies for Heterogeneous Application and Server Environments

In a multimedia system, storage and bandwidth are critical resources since any presentation requires a large volume of data to be delivered in real-time. Caching of multimedia documents in local storage can alleviate large retrieval bandwidth requirements. An important requirement for a multimedia caching policy is to guarantee continuous delivery even when a stream is served from cache. It should also cope with dynamic changes in workload and heterogeneity arising from large and small multimedia files. The proposed Generalized Interval Caching (GIC) policy, that caches intervals between successive streams of a large file as well as entire small files, satisfies all the above criteria. A caching policy needs to cope with additional challenges in a large scale distributed multimedia environment consisting of many heterogeneous servers. The issues include a) routing of requests to ensure good cache hits in each server, and b) balancing of loads across servers. For routing of requests, we introduce the notion of an asset group and propose an affinity routing policy based on this concept. Finally, we adapt the GIC policy for load balancing across servers.     

Storage bins: mobile storage for collaborative tabletop displays

The ability to store resource items anywhere in the workspace and move them around can be critical for coordinating task and group interactions on a table. However, existing casual storage techniques for digital workspaces only provide access to stored items at the periphery of the workspace, potentially compromising collaborative interactions at a digital tabletop display. To facilitate this storage behavior in a digital tabletop workspace, we developed the storage bin mobile storage mechanism, which combines the space-preserving features of existing peripheral storage mechanisms with the capability to relocate stored items in the workspace. A user study explores the utility of storage bins on tabletop display collaboration.