University of Pacific
Today's network file systems consist of a variety of complex sub-protocols and backend storage classes. The data is typically spread over multiple data servers to achieve higher levels of performance and reliability. A metadata server is responsible for creating the mapping of a file to these data servers. It is hard to map application specific access patterns to storage system specific features, which can result in a degraded IO performance. The authors present an NFSv4.1 / pNFS protocol extension that integrates the client's ability to provide hints and I/O advices to metadata servers. They define multiple storage classes and allow the client to choose which type of storage fits best for its desired access pattern.