Server-side prefetching in distributed file systems

摘要

This paper presents a proactive data prefetching mechanism on storage servers for distributed file systems to achieve better input/output (I/O) performance. This mechanism requires keeping tracks of what blocks were accessed and the information about client I/O requests to predict which blocks will be accessed in the future. Except for showing a linear access tendency, I/O access operations on blocks also reveal a random or similar-random tendency but with certain access patterns. Thus, to address the prediction for future possible read operations, a linear regression algorithm and a chaotic prediction algorithm have been proposed to forecast the future access requests according to different access patterns. As a result, by employing the information, that is, offsets and request sizes, about the predicted future read requests on disk blocks, the storage servers in our newly presented mechanism can prefetch block data more precisely and then send it to associated client file system proactively. The experimental results illustrate that our proposed mechanism is able to shorten read latency to a great extent and then contribute to better read throughput significantly in certain application contexts. Copyright © 2014 John Wiley & Sons, Ltd.