This paper presents Cluster-Aware Remote Disks (CARDs), a Single System I/O architecture for cluster computing. CARDs virtualize accesses to remote cluster disks over a System Area Network. Their operation is driven by cooperative caching policies that implement a joint management of the cluster caches. All the CARDs of a given disk employ a common policy, independently of other CARD sets. CARD drivers have been implemented as Linux kernel modules which can flexibly accommodate various cooperative caching algorithms. We designed and implemented a decentralized policy called Home-based Serverless Cooperative Caching (HSCC). HSCC showed cache hit ratios over 50 % for workloads that go beyond the limit of the global cache. The best speedup of a CARD over a remote disk interface was 1.54. 1

Parallel and distributed computing have matured sufficiently for their adoption in production environments, consequently necessitating effective, robust, and efficient frameworks for input and output. A number of concurrent I/O initiatives have evolved in response to these needs, some system specific, others proposing an abstract framework and portable interface. These parallel and distributed I/O efforts focus either on characterizing file access patterns, language extensions, runtime libraries, or low level primitives. Important systems issues in each approach, technical details of various strategies, and their effect on performance are analyzed. The PIOUS system, a transport independent, scalable I/O framework for parallel and distributed systems is presented, and experiences with its use are reported. 1 Introduction It is well documented that the performance of many scientific and commercial applications, including the Grand Challenge problems [4], is often limited by the performa...

Disk-directed I/O for an Out-of-core Computation New file systems are critical to obtain good I/O performance on large multiprocessors. Several researchers have suggested the use of collective file-system operations, in which all processes in an application cooperate in each I/O request. Others have suggested that the traditional lowlevel interface (read, write, seek) be augmented with various higher-level requests (e.g., read matrix). Collective, high-level requests permit a technique called diskdirected I/O to significantly improve performance over traditional file systems and interfaces, at least on simple I/O benchmarks. In this paper, we present the results of experiments with an “out-of-core ” LU-decomposition program. Although its collective interface was awkward in some places, and forced additional synchronization, diskdirected I/O was able to obtain much better overall performance than the traditional system. 1

Caching is a technique intensively used in memory and traditional file systems to improve system performance. However, the use of caching in parallel file systems has been limited to I/O nodes to avoid cache coherence problems. In this paper we present the cache policies implemented in ParFiSys, a parallel file system developed at the UPM. ParFiSys exploits the use of cache both at computing nodes and I/O nodes, with aggressive prefetching and delayed-write techniques. The cache coherence problem is solved using a dynamic scheme of cache coherence protocols with different sizes and shapes of granularity. Some performance results, obtained on an IBM SP2, are presented to demonstrate advantages offered by the cache management used in ParFiSys. Resumen El concepto de cache ha sido ampliamente utilizado en memoria y sistemas de ficheros tradicionales como un mecanismo para mejorar el rendimiento del sistema. Sin embargo, el uso de cache en sistemas de ficheros paralelos se ha limitado exc...