Efficient Approaches for Metadata Prefetching and Data Placement in Wide-Area Computing

Abstract

Metadata prefetching and data placement are essential to improve access performance for wide-area network file systems. Constructing efficient approaches has been a challenge for metadata prefetching in concurrent workload scenarios and for data placement in a wide-area network. This paper proposes efficient approaches for metadata prefetching and data placement, wherein fine-grained control of prefetching policies and variable-size data fragment writing are utilized to maximize the I/O bandwidth of distributed files. The proposed metadata prefetching approach dynamically detects the dominant workload and adaptively adjusts the prefetching policy to improve metadata access performance in concurrent workload scenarios. The proposed data placement approach places the written data fragments into the local data center to improve the write performance and sends only the location information of the data fragments to the remote data center that holds the original file. Experimental results using real system traces indicate that the file system metadata and application data access times can be reduced by up to 33.5% and 17.19%, respectively, compared to that of state-of-the-art methods.