并行文件系统扩容与I/O节点负载平衡策略

在规模并行处理系统ＭＰＰ商业化应用中,并行文件系统容量与Ｉ／Ｏ节点的负载平衡一直是挖掘整个系统并行性,进而提高系统性能的关键问题之一。本文从分析Ｐａｒａｇｏｎ大规模并行处理系统的体系结构和并行文件系统的体系结构出发,给出了并行文件系统的扩容策略,使用ＭＰＰ系统的Ｉ／Ｏ节点平衡负载理论模型,给出了实际工程应用中的负载平衡策略。     

UNIX／XENIX系统磁盘文件的存取及转换

ZZX在UNIX／XENIX系统下，文件存放在软盘上分为块I／O格式（文件系统格式，即通常说的mount格式）和字符I／O格式（即通常说的tar格式）两种。这是两种不同的使用软盘的方法，它们是不能混用的，也是完全不兼容的。1块I／O格式磁盘文件块格式的磁盘文件，即访问数据要以固定长度的块进行，又称文件系统格式。这种格式磁盘文件的存取必须首先使用mount命令将其作为文件系统安装在UNIX／XENIX根文件系统的空目录上（如／mnt或自行建立的空目录上），然后可以像使用根文件系统的任何一个于目录一样使用这个软盘，可以使用各种随机…     

MPP的并行I／O子系统

ＭＰＰ的峰值速度可望在近年内达到每秒十万亿次，主要用于大数据量的计算。所以，如果ＭＰ中的Ｉ／Ｏ性能不能得到迅速提高，ＭＰＰ的整体性能将会肥到严重影响。也就是说，Ｉ／Ｏ性能决定着ＭＰＰ的总体性能。     

并行文件系统PFS的设计与分析

并行计算机高速处理能力与低速Ｉ／Ｏ设备之间的矛盾目前已成为并行计算机系统中的主要问题之一，因此必须研制高性能的并行文件系统．。本文介绍的ＰＦＳ是为“八六三计划”中“曙光二号”并行计算机设计的并行文件系统，该ＰＦＳ分散Ｉ／Ｏ设备的管理到多个处理结点，使文件能交叉地分布在不同Ｉ／Ｏ结点所控制的物理设备上，以实现最大程度的并行访问。本文阐述了ＰＦＳ的基本设计、实现方法及其性能的粗略分析。     

XENIX下误删文件的恢复方法

在XENIX系统中，常发生因使用rm命令而不慎将文件误删的情况，但只要此时再没人使用系统建立新文件，删除的文件是可以恢复的。因为rm命令只是把文件在文件系统中的i节点（inod）信息清除，而文件的正文信息与数据信息占据的磁盘块还未被清除，此时只要找到这些磁盘块，重建文件的i节点，便可拯救误删文件。＊＊＊IX文件系统有如下结构：见图1）ffil当文件被删除时，其占据的磁盘块被依次压栈到空闲块索引表（fieblocklist）的顶部，索引表位于文件系统超级专用块（superblock）的首端。我们只要从索引表里找出这些块号，填入i节点区内，…     

SPP并行I／O处理机的设计与实现

可扩展并行处理机系统有两个需要解决的问题：（１）多级互连网络的延迟；（２）吞吐能力；本文根据ＳＰＰ体系结构的特点和实际应用的需要提出了解决这两个瓶颈问题的有效方法在前端服务器与共享存储器之间设计专用的并行Ｉ／Ｏ处理机作为系统Ｉ／Ｏ设备与ＳＭ／ＳＳＭ的直接数据通路。     

XENIX系统误删文件的恢复

在XENIX系统中，常因使用rm命令而不慎将文件误删的情况，只要没人使用系统建立新文件，删除的文件是可以恢复的。因为rm命令只是把文件在文件系统中的i节点（inode）信息清除，而文件的正文信息与数据信息占据的磁盘块还未被清理。XENIX文件系统有如下结构当文件被删除时，其占据的磁盘块被依次压栈到空闲块索引表（freeblocklist）的顶部。索引表位于文件系统超级专用块（superblock）的2号块首端，我们只要从索引表里找出这些块号，填入i节点区内，重构文件的i节点，可使被删除的文件得以恢复。下面以scoxenixVrelease2．3．2的根文…     

两条PCI多流并发I/O结点实现技术研究

当微处理器速度快速提高的同时,受限于机电等因素的Ｉ／Ｏ性能却难以同步增长,因而许多应用程序如天气预报,石油地震数据分析等在ＭＰＰ上运行时文伯Ｉ／Ｏ总是瓶颈。为了提高Ｉ／Ｏ性能,提出两条ＰＣＩ总线多流并发Ｉ／ＯＮ设计实现方案。     

采用C和C++文件函数自定义小型汉字库实例

１　Ｃ和Ｃ＋＋文件函数　　Ｃ或Ｃ＋＋都提供了两类关于文件的函数,一类是标准文件函数,另一类是非标准文件函数。标准文件函数,即有缓冲区的输入和输出（ＢｕｆｆｅｒｅｄＩ／Ｏ）,又称高级磁盘输入输出（高级Ｉ／Ｏ）。非标准文件函数,即无缓冲区的输入和输出（ＵｎｂｕｆｆｅｒｅｄＩ／Ｏ）,又称低级输入和输出（低级Ｉ／Ｏ）,表示输入和输出的动作是直接在磁盘内执行读写信息的动作。对这两种文件操作,Ｃ和Ｃ＋＋是放在不同库中。Ｃ和Ｃ＋＋标准文件函数是包含在ｓｔｄｉｏ．ｈ文件中,而非标准文件函数是包含在ｆｃｎｔｌ．ｈ…     

在WIN95下删除NTFS分区的方法

Ｗｉｎｄｏｗ９５、Ｗｉｎｄｏｗ９８、ＷｉｎｄｏｗｓＮＴ操作系统是Ｍｉｃｒｏｓｉｆｔ公司近年推出的十分优秀的计算机工作平台。它在社会上得以广泛的使用,颇受欢迎。ＷｉｎｄｏｗｓＮＴ支持的文件系统包括：　ＦＡＴ　（文件分配表,主要用于ＤＯＳ操作系统）;　ＨＰＦＳ　（高性能文件系统,主要用于ＯＳ／２操作系统）;　ＣＤＦＳ　（ＣＤ文件系统,主要用于ＣＤＲＯＭ文件）;　ＮＴＦＥ　（ＮＴ文件系统,ＷｉｎｄｏｗｓＮＴ特有）。其中ＮＴＦＳ文件系统是ＷｉｎｄｏｗｓＮＴ操作系统独有的文件管理系统。它具有很好的安全性和…     

集群计算并行I/O中动态文件分配策略

针对集群计算系统中并行I／O文件分配问题进行了研究,提出一种新的动态文件分配算法一启发式负载与服务时间变化综合平衡策略。该策略将所需要的访问服务时间相似的文件分配到集群系统的同一结点磁盘上,并保证每个磁盘上的负载值不超过负载平衡的极限值,从而在所有结点磁盘间既基本实现负载均衡,又使每个磁盘上文件间的服务时间变化最小化。实验结果表明了该策略在性能提高方面的有效性。     

并行文件系统的关键技术与框架设计

论述并行文件系统的工作负载特征——基于空间和时间的文件访问模式，并对非连续数据访问技术进行比较研究；给出并行文件系统设计的原则与目标，最后提出并行文件系统的框架。     

高强度I/O的应用对并行存储系统的挑战和解决方法研究

具有高I/O密集特性的高性能计算应用对高性能计算机存储系统综合性能的要求越来越高.以石油地震勘探数据处理为代表的一类重要应用表现出I/O数据量巨大、I/O访问密度大,对单个磁盘阵列存储部件的读写带宽要求高的特征.在Lustre文件系统中,充当对象存储服务功能的磁盘阵列设备输出带宽的不足将成为阻碍存储系统整体性能发挥的重要因素.针对此类问题,提出了一种缓存管理方法,分别在客户端添加VDISK模块,在OST端添加Cache模块,二者协同提高并行文件系统I/O的输出带宽的使用效率;另外,充分利用客户端空闲内存以及客户端之间的通信带宽,降低应用程序对磁盘阵列设备输出带宽的要求.通过大规模并行模型的验证表明,VDISK提高了实际可用的输出带宽,提高了外部存储系统的I/O效率.     

Input/output optimization and disk architectures: A survey

The file system, and the components of the computer system associated with it (disks, drums, channels, mass storage, tapes and tape drives, controllers, I/O drivers, etc.) comprise a very substantial fraction of most computer systems; substantial in several aspects including amount of operating system code, expense for components, physical size and effect on performance. In this paper we survey the state of the art file and I/O system design and optimization as it applies to large data processing installations. In a companion paper, some research results applicable to both current and future system designs are summarized.Among the topics we discuss is the optimization of current file systems, where some material is provided regarding block size choice, data set placement, disk arm scheduling, rotational scheduling, compaction, fragmentation, I/O multipathing and file data structures. A set of references to the literature, especially to analytic I/O system models, is presented. The general tuning of file and I/O systems is also considered. Current and forthcoming disk architectures are the second topic. The count key data architecture of current disks (e.g. IBM 3350, 3380) and the fixed block architecture of new products (IBM 3310, 3370) are compared. The use of semiconductor drum replacements is considered and some commercially available systems are briefly described.     

Gfarm Grid File System

Gfarm Grid file system is a global distributed file system to share data and to support distributed data-intensive computing. It federates local file systems on compute nodes to maximize distributed file I/O bandwidth, and allows to store multiple file replicas in any location to avoid read access concentration of hot files. Data location aware process scheduling improves the file I/O performance of distributed data-intensive computing. This paper discusses the design and implementation of the Gfarm Grid file system, and reports the performance.     

Reducing I/O variability using dynamic I/O path characterization in petascale storage systems

In petascale systems with a million CPU cores, scalable and consistent I/O performance is becoming increasingly difficult to sustain mainly because of I/O variability. The I/O variability is caused by concurrently running processes/jobs competing for I/O or a RAID rebuild when a disk drive fails. We present a mechanism that stripes across a selected subset of I/O nodes with the lightest workload at runtime to achieve the highest I/O bandwidth available in the system. In this paper, we propose a probing mechanism to enable application-level dynamic file striping to mitigate I/O variability. We implement the proposed mechanism in the high-level I/O library that enables memory-to-file data layout transformation and allows transparent file partitioning using subfiling. Subfiling is a technique that partitions data into a set of files of smaller size and manages file access to them, making data to be treated as a single, normal file to users. We demonstrate that our bandwidth probing mechanism can successfully identify temporally slower I/O nodes without noticeable runtime overhead. Experimental results on NERSC’s systems also show that our approach isolates I/O variability effectively on shared systems and improves overall collective I/O performance with less variation.     

基于热度的Hadoop快速副本复制算法

在云存储中心, 由于节点失效带来的文件数据块副本丢失不仅会影响系统的可靠性, 还会影响文件的并发访问效率. 针对Hadoop中默认的副本复制方法存在的问题, 即副本复制过程某些节点数据传输过于集中, 负载不均衡, 磁盘I/O吞吐率低, 提出一种基于热度的快速副本复制算法. 该算法优先复制热度高的数据块, 合理选择数据块复制的源节点和目的节点. 仿真结果表明, 该算法平衡了系统的工作负载, 提高了磁盘I/O吞吐率, 显著降低用户请求平均响应时间.     

Towards minimizing disk I/O contention: A partitioned file assignment approach

One problem with data-intensive computing facilitating is how to effectively manage massive amounts of data stored in a parallel I/O system. The file assignment method plays a significant role in data management. However, in the context of a parallel I/O system, most existing file assignment approaches share the following two limitations. First, most existing methods are designed for a non-partitioned file, while the file in a parallel I/O system is generally partitioned to provide aggregated bandwidth. Second, the file allocation metric, e.g. service time, of most existing methods is difficult to determine in practice, and also these metrics only reflect the static property of the file. In this paper, a new metric, namely file access density is proposed to capture the dynamic property of file access, i.e. disk contention property. Based on file access density definition, this paper introduces a new static file assignment algorithm named MinCPP and its dynamic version DMinCPP, both of which aim at minimizing the disk contention property. Furthermore MinCPP and DMinCPP take the file partition property into consideration by trying to allocate the partitions belonging to the same file onto different disks. By assuming file request arrival follows the Poisson process, we prove the effectiveness of the proposed schemes both analytically and experimentally. The MinCPP presented in this study can be applied to reorganize the files stored in a large-scale parallel I/O system and the DMinCPP can be integrated into file systems which dynamically allocate files in a batch.     

Reference implementation of scalable I/O low-level API on Intel Paragon

The Scalable I/O(SIO)Initiative‘s Low-Level Application Programming Interface(SIO LLAP)provides file system implementers with a simple low-Level interface to support high-level parallel /O interfaces efficiently and effectively.This paper describes a reference implementation and the evaluation of the SIO LLAPI on the Intel Paragon multicomputer.The implementation provides the file system structure and striping algorithm compatible with the Parallel File System(PFS)of Intel Paragon ,and runs either inside the kernel or as a user level library.The scatter-gather addressing read/write,asynchronous I/O,client caching and prefetching mechanism,file access hint mechanism,collective I/O and highly efficient file copy have been implemented.The preliminary experience shows that the SIO LLAPI provides opportunities of significant performance improvement and is easy to implement.Some high level file system interfaces and applications such as PFS,ADIO and Hartree-Fock application,are also implemented on top of SIO.The performance of PFS is at least the same as that of Intel‘s native pfs,and in many cases,such as small sequential file access,huge I/O requests and collective I/O,it is stable and much better,The SIO features help to support high level interfaces easily,quickly and more efficiently,and the cache,prefetching,hints are useful to get better performance based on different access models.The scalability and performance of SIO are limited by the network latency,network scalable bandwidth,memory copy bandwidth,memory size and pattern of I/O requests.The tadeoff between generality and efficienc should be considered in implementation.