Making the Most out of Direct-Access Network Attached Storage

The performance of high-speed network-attached storage applications is often limited by end-system overhead, caused primarily by memory copying and network protocol processing. In this paper, we examine alternative strategies for reducing overhead in such systems. We consider optimizations to remote procedure call (RPC)-based data transfer using either remote direct memory access (RDMA) or network interface support for pre-posting of application receive buffers. We demonstrate that both mechanisms enable file access throughput that saturates a 2Gb/s network link when performing large I/Os on relatively slow, commodity PCs. However, for multi-client workloads dominated by small I/Os, throughput is limited by the per-I/O overhead of processing RPCs in the server. For such workloads, we propose the use of a new network I/O mechanism, Optimistic RDMA (ORDMA). ORDMA is an alternative to RPC that aims to improve server throughput and response time for small I/Os. We measured performance improvements of up to 32% in server throughput and 36% in response time with use of ORDMA in our prototype.Engineering and Applied Science

Design and Implementation of ORFA

ORFA is a user-level protocol that aims at providing an efficient remote file system access. It uses high bandwidth local networks and their specific API to directly connect user programs to data in the remote server. The ORFA model and its first implementation are described in this paper. The client is an automatically preloaded shared library that transparently overrides glibc I/O calls and redirect them to the server if concerned files are remote. The server may be a user program implementing a custom memory file system, or accessing native file systems

Efficient Interaction between High-Speed Networks and Distributed Storage in Clusters

Parallel applications running on clusters require both high-performance communications between nodes and efficient access to the storage system. We propose to improve the performance of distributed storage systems in clusters by efficiently using the underlying high-performance network to access distant storage systems. We show that storage requirements are very different from those of parallel computation and that a modification of the network programming interface is required. We detail several propositions for these interfaces which make their utilization easier in the context of distributed storage. Performance evaluations show that their integration makes it easy to use and very efficient in the context of storage

Interaction efficace entre les réseaux rapides et le stockage distribué dans les grappes de calcul

National audienceLes applications parallèles s'exécutant sur les grappes nécessitent à la fois des communications performantes entre les différents noeuds et des accès efficaces au système de stockage. Nous proposons dans ce travail d'améliorer les performances du stockage distribué dans les grappes en utilisant au mieux le réseau haute performance sous-jacent. Nous montrons que les besoins du stockage sont très différents de ceux du calcul parallèle et proposons différentes solutions pour résoudre, les problèmes liés au contrôle du réseau mais montrons qu'il est nécessaire de modifier l'interface de programmation réseau et le système d'explotation pour venir à bout des difficultés liées au transfert de données. Des expérimentations montrent qu'elles permettent une utilisation aisée et efficace des réseaux rapides dans le cadre du stockage distribué