Network storage increase capacity and scalability of storage system, data availability and enables the sharing of data among clients. When the developing network technology reduce performance gap between disk and netw...Network storage increase capacity and scalability of storage system, data availability and enables the sharing of data among clients. When the developing network technology reduce performance gap between disk and network, however, mismatched policies and access pattern can significantly reduce network storage performance. So the strategy of data placement in system is an important factor that impacts the performance of overall system. In this paper, the two algorithms of file assignment are presented. One is Greed partition that aims at the load balance across all NADs (Network Attached Disk). The other is Sort partition that tries to minimize variance of service time in each NAD. Moreover, we also compare the performance of our two algorithms in practical environment. Our experimental results show that when the size distribution (load characters) of all assigning files is closer and larger, Sort partition provides consistently better response times than Greedy algorithm. However, when the range of all assigning files is wider, there are more small files and access rate is higher, the Greedy algorithm has superior performance in compared with the Sort partition in off-line.展开更多
We put forward an optimal disk schedule with n disk requests and prove its optimality mathematically.Generalizing the idea of an optimal disk schedule, we remove the limit of n requests and, at the same time, consider...We put forward an optimal disk schedule with n disk requests and prove its optimality mathematically.Generalizing the idea of an optimal disk schedule, we remove the limit of n requests and, at the same time, consider the dynamically arrival model of disk requests to obtain an algorithm, shortest path first-fit first （SPFF）. This algorithm is based on the shortest path of disk head motion constructed by all the pendent requests. From view of the head moving distance, it has the stronger glohality than SSTF. From view of the head-moving direction, it has the better flexibility than SCAN. Therefore, SPFF keeps the advantage of SCAN and, at the same time, absorbs the strength of SSTF. The algorithm SPFF not only shows the more superiority than other scheduling polices, but also have higher adjustability to meet the computer system＇s different demands.展开更多
We propose a network-attached storage system that can support guaranteed Quality of Service （QoS）, called POPNet Storage. The special policy of date access and disk scheduling is enable users to access files quickly...We propose a network-attached storage system that can support guaranteed Quality of Service （QoS）, called POPNet Storage. The special policy of date access and disk scheduling is enable users to access files quickly and directly with guaranteed QoS in the POPNet Storage. The POPNet Storage implements a measurement-based admission control algorithm （PSMBAC） to determine whether to admit a new data access request stream and admit as many requests as possible while meeting the QoS guarantees to its clients. The data reconstruction algorithms in the POPNet Storage also put more emphasis on data availability and guaranteed QoS, thus it is designed to complete the data recovery as soon as possible and at the same time provide the guaranteed QoS for high-priority data access. The experiment results show that the POPNet Storage can provide more significant performance, reliability, and guaranteed QoS than conventional storage systems.展开更多
针对数据存储中心硬盘故障数据稀少造成的故障预测效果不佳的问题,面向自我检测分析与报告技术(self-monitoring analysis and reporting technology,SMART)数据信息的时序特征,提出一种通过数据增强解决不平衡问题的硬盘故障预测算法...针对数据存储中心硬盘故障数据稀少造成的故障预测效果不佳的问题,面向自我检测分析与报告技术(self-monitoring analysis and reporting technology,SMART)数据信息的时序特征,提出一种通过数据增强解决不平衡问题的硬盘故障预测算法。该算法利用长短期记忆网络改进传统的生成对抗网络,生成包含故障恶化趋势信息的序列段数据,解决了数据集不平衡问题。同时,为进一步提高预测性能,预测模型融合了时序注意力机制和特征注意力机制,挖掘不同SMART特征和时间步对硬盘故障恶化过程的敏感程度。此外,在特征选择阶段结合了多种典型特征选择算法来选取关键特征。在真实硬盘数据集上进行了实验验证,结果表明,所提算法的准确率、召回率和F 1值均有较大提升。展开更多
面向企业网或校园网的移动办公与存储的网盘系统有着广泛的市场需求,传统的网盘技术在性能、用户共享、安全性、可扩展性等方面存在诸多缺陷。针对这些不足,本文提出了一种基于云存储的高性能网盘系统架构:采用分布式文件系统MooseFS实...面向企业网或校园网的移动办公与存储的网盘系统有着广泛的市场需求,传统的网盘技术在性能、用户共享、安全性、可扩展性等方面存在诸多缺陷。针对这些不足,本文提出了一种基于云存储的高性能网盘系统架构:采用分布式文件系统MooseFS实现用户数据存储与访问的集群架构;在安全性方面,结合SAMBA实现用户权限管理,用户数据存储支持128 bit AES加密,SSH保证了传输链路的安全;最后,结合用户的实际需求,提供基于Web的访问方式以及客户端的同步盘模式。结果表明,系统在性能、安全性、可扩展性等多方面具有显著优势。展开更多
针对传统电机输出端口单一的问题,提出一种新型多端口盘式永磁电机(multi-port disk permanent magnet motor,MDPMM)。首先,介绍该电机的结构及工作原理;其次,针对该电机环形弧线定子周向端部使其漏磁和磁场分布较为复杂的问题,引入磁...针对传统电机输出端口单一的问题,提出一种新型多端口盘式永磁电机(multi-port disk permanent magnet motor,MDPMM)。首先,介绍该电机的结构及工作原理;其次,针对该电机环形弧线定子周向端部使其漏磁和磁场分布较为复杂的问题,引入磁通分布系数,对受环形弧线定子端部影响的区域建立等效磁网络模型,计算各等效磁阻,解析该区域漏磁系数表达式;最后,考虑永磁体电流密度等效,建立环形弧线定子及对应盘式转子区域的分区域解析模型,运用等效磁化强度法推导该区域气隙磁场解析式,并采用许−克变换分析定子齿槽结构对气隙磁场的影响。研究结果表明:该电机可以同时实现双盘式转子和行星轮转子多自由度动力输出;受环形弧线定子端部截面影响和未受影响的2种磁路的气隙漏磁系数计算值分别为1.263、1.167,有限元仿真值分别为1.375、1.222,计算值和仿真值的相对误差分别为8.15%、4.50%;2种磁路的平均气隙磁密计算值分别为0.481、0.492,有限元仿真值分别为0.497、0.503,计算值和仿真值的相对误差分别为3.22%、2.19%,满足工程计算精度要求。展开更多
文摘Network storage increase capacity and scalability of storage system, data availability and enables the sharing of data among clients. When the developing network technology reduce performance gap between disk and network, however, mismatched policies and access pattern can significantly reduce network storage performance. So the strategy of data placement in system is an important factor that impacts the performance of overall system. In this paper, the two algorithms of file assignment are presented. One is Greed partition that aims at the load balance across all NADs (Network Attached Disk). The other is Sort partition that tries to minimize variance of service time in each NAD. Moreover, we also compare the performance of our two algorithms in practical environment. Our experimental results show that when the size distribution (load characters) of all assigning files is closer and larger, Sort partition provides consistently better response times than Greedy algorithm. However, when the range of all assigning files is wider, there are more small files and access rate is higher, the Greedy algorithm has superior performance in compared with the Sort partition in off-line.
基金Supported by the National Natural Science Founda-tion of China (60373088)
文摘We put forward an optimal disk schedule with n disk requests and prove its optimality mathematically.Generalizing the idea of an optimal disk schedule, we remove the limit of n requests and, at the same time, consider the dynamically arrival model of disk requests to obtain an algorithm, shortest path first-fit first （SPFF）. This algorithm is based on the shortest path of disk head motion constructed by all the pendent requests. From view of the head moving distance, it has the stronger glohality than SSTF. From view of the head-moving direction, it has the better flexibility than SCAN. Therefore, SPFF keeps the advantage of SCAN and, at the same time, absorbs the strength of SSTF. The algorithm SPFF not only shows the more superiority than other scheduling polices, but also have higher adjustability to meet the computer system＇s different demands.
文摘We propose a network-attached storage system that can support guaranteed Quality of Service （QoS）, called POPNet Storage. The special policy of date access and disk scheduling is enable users to access files quickly and directly with guaranteed QoS in the POPNet Storage. The POPNet Storage implements a measurement-based admission control algorithm （PSMBAC） to determine whether to admit a new data access request stream and admit as many requests as possible while meeting the QoS guarantees to its clients. The data reconstruction algorithms in the POPNet Storage also put more emphasis on data availability and guaranteed QoS, thus it is designed to complete the data recovery as soon as possible and at the same time provide the guaranteed QoS for high-priority data access. The experiment results show that the POPNet Storage can provide more significant performance, reliability, and guaranteed QoS than conventional storage systems.
文摘面向企业网或校园网的移动办公与存储的网盘系统有着广泛的市场需求,传统的网盘技术在性能、用户共享、安全性、可扩展性等方面存在诸多缺陷。针对这些不足,本文提出了一种基于云存储的高性能网盘系统架构:采用分布式文件系统MooseFS实现用户数据存储与访问的集群架构;在安全性方面,结合SAMBA实现用户权限管理,用户数据存储支持128 bit AES加密,SSH保证了传输链路的安全;最后,结合用户的实际需求,提供基于Web的访问方式以及客户端的同步盘模式。结果表明,系统在性能、安全性、可扩展性等多方面具有显著优势。
文摘针对传统电机输出端口单一的问题,提出一种新型多端口盘式永磁电机(multi-port disk permanent magnet motor,MDPMM)。首先,介绍该电机的结构及工作原理;其次,针对该电机环形弧线定子周向端部使其漏磁和磁场分布较为复杂的问题,引入磁通分布系数,对受环形弧线定子端部影响的区域建立等效磁网络模型,计算各等效磁阻,解析该区域漏磁系数表达式;最后,考虑永磁体电流密度等效,建立环形弧线定子及对应盘式转子区域的分区域解析模型,运用等效磁化强度法推导该区域气隙磁场解析式,并采用许−克变换分析定子齿槽结构对气隙磁场的影响。研究结果表明:该电机可以同时实现双盘式转子和行星轮转子多自由度动力输出;受环形弧线定子端部截面影响和未受影响的2种磁路的气隙漏磁系数计算值分别为1.263、1.167,有限元仿真值分别为1.375、1.222,计算值和仿真值的相对误差分别为8.15%、4.50%;2种磁路的平均气隙磁密计算值分别为0.481、0.492,有限元仿真值分别为0.497、0.503,计算值和仿真值的相对误差分别为3.22%、2.19%,满足工程计算精度要求。
