The size and complexity of large storage systems, such as high-performance computing (HPC) systems, inhibit rapid effective restructuring of data layouts to maintain performance as workloads shift. To address this issue, we have developed Geomancy, a tool that models the placement of data within a distributed storage system and reacts to drops in performance. Our approach to optimizing throughput offers benefits for storage systems such as avoiding potential bottlenecks and increasing overall I/O throughput from 11% to 30%.

Data Grids are currently proposed solutions to large scale data management problems including efficient file transfer and replication. Large amounts of data and the world-wide distribution of data stores contribute to the complexity of the data management challenge. Recent architecture proposals and prototypes deal with replication of read-only files but do not address the replica synchronisation problem. We propose a new Grid service, called Grid Consistency Service (GCS), that sits on top of existing Data Grid services and allows for replica update synchronisation and consistency maintenance. We give models for different levels of consistency provided to the Grid user and discuss how they can be included into a replica consistency service for a Data Grid. 1