The GridFTP extensions to the File Transfer Protocol define a general-purpose mechanism for secure, reliable, high-performance data movement. We report here on the Globus striped GridFTP framework, a set of client and server libraries designed to support the construction of data-intensive tools and applications. We describe the design of both this framework and a striped GridFTP server constructed within the framework. We show that this server is faster than other FTP servers in both single-process and striped configurations, achieving, for example, speeds of 27.3 Gbit/s memory-to-memory and 17 Gbit/s disk-to-disk over a 60 millisecond round trip time, 30 Gbit/s network. In another experiment, we show that the server can support 1800 concurrent clients without excessive load. We argue that this combination of performance and modular structure make the Globus GridFTP framework both a good foundation on which to build tools and applications, and a unique testbed for the study of innovative data management techniques and network protocols.

/pdf/the-globus-striped-gridftp-framework-and-server-2rlwq5ow1f.pdf

The Globus Striped GridFTP Framework and Server

The Globus project is a multi-institutional research effort that seeks to enable the construction of computational grids providing pervasive, dependable, and consistent access to high-performance computational resources, despite geographical distribution of both resources and users. Computational grid technology is being viewed as a critical element of future high-performance computing environments that will enable entirely new classes of computation-oriented applications, much as the World Wide Web fostered the development of new classes of information-oriented applications. The authors report on the status of the Globus project as of early 1998. They describe the progress that has been achieved to date in the development of the Globus toolkit, a set of core services for constructing grid tools and applications. They also discuss the Globus Ubiquitous Supercomputing Testbed (GUSTO) that they have constructed to enable large-scale evaluation of Globus technologies, and they review early experiences with the development of large-scale grid applications on the GUSTO testbed.

/pdf/the-globus-project-a-status-report-54lj064yc6.pdf

The Globus project: a status report

We discuss the issues involved in implementing MPI-IO portably on multiple machines and file systems and also achieving high performance. One way to implement MPI-IO portably is to implement it on top of the basic Unix I/O functions (open, lseek, read, write, and close), which are themselves portable. We argue that this approach has limitations in both functionality and performance. We instead advocate an implementation approach that combines a large portion of portable code and a small portion of code that is optimized separately for different machines and file systems. We have used such an approach to develop a high-performance, portable MPI-IO implementation, called ROMIO. In addition to basic I/O functionality, we consider the issues of supporting other MPI-IO features, such as 64-bit file sizes, noncontiguous accesses, collective I/O, asynchronous I/O, consistency and atomicity semantics, user-supplied hints, shared file pointers, portable data representation, and file preallocation. We describe how we implemented each of these features on various machines and file systems. The machines we consider are the HP Exemplar, IBM SP, Intel Paragon, NEC SX-4, SGI Origin2000, and networks of workstations; and the file systems we consider are HP HFS, IBM PIOFS, Intel PFS, NEC SFS, SGI XFS, NFS, and any general Unix file system (UFS). We also present our thoughts on how a file system can be designed to better support MPI-IO. We provide a list of features desired from a file system that would help in implementing MPI-IO correctly and with high performance.

/pdf/on-implementing-mpi-io-portably-and-with-high-performance-57ox0doa1w.pdf

On implementing MPI-IO portably and with high performance

In wide area computing, programs frequently execute at sites that are distant from their data. Data access mechanisms are required that place limited functionality demands on an application or host system yet permit high-performance implementations. To address these requirements, we propose a data movement and access service called Global Access to Secondary Storage (GASS). This service defines a global name space via Uniform Resource Locators and allows applications to access remote files via standard I/O interfaces. High performance is achieved by incorporating default data movement strategies that are specialized for I/O patterns common in wide area applications and by providing support for programmer management of data movement. GASS forms part of the Globus toolkit, a set of services for high-performance distributed computing. GASS itself makes use of Globus services for security and communication, and other Globus components use GASS services for executable staging and real-time remote monitoring. Application experiences demonstrate that the library has practical utility.

https://courses.cs.vt.edu/~cs5204/fall05-kafura/Papers/Grids/gass.pdf

GASS: a data movement and access service for wide area computing systems

We describe a framework, called DataCutter, that is designed to provide support for subsetting and processing of datasets in a distributed and heterogeneous environment. We illustrate the use of DataCutter with several data-intensive applications from diverse fields, and present experimental results.

Distributed processing of very large datasets with DataCutter

As high-speed networks make it easier to use distributed resources, it becomes increasingly common that applications and their data are not colocated. Users have traditionally addressed this problem by manually staging data to and from remote computers. We argue instead for a new remote I/O paradigm in which programs use familiar parallel I/O interfaces to access remote file systems. In addition to simplifying remote execution, remote I/O can improve performance relative to staging by overlapping computation and data transfer or by reducing communication requirements. However, remote I/O also introduces new technical challenges in the areas of portability, performance, and integration with distributed computing systems. We propose techniques designed to address these challenges and describe a remote I/O library called RIO that we have developed to evaluate the effectiveness of these techniques. RIO addresses issues of portability by adopting the quasi-standard MPI-IO interface and by defining a RIO device and RIO server within the ADIO abstract I/O device architecture. It addresses performance issues by providing traditional I/O optimizations such as asynchronous operations and through implementation techniques such as buffering and message forwarding to off load communication overheads. RIO uses the Nexus communication library to obtain access to configuration and security mechanisms provided by the Globus wide area computing tool kit. Microbenchmarks and application experiments demonstrate that our techniques achieve acceptable performance in most situations and can improve turnaround time relative to staging.

/pdf/remote-i-o-fast-access-to-distant-storage-488cqcdgow.pdf

Jace Mogill

Papers

Remote I/O: fast access to distant storage