CTFS: a new lightweight, cooperative temporary file system for cluster-based Web servers

Previous studies showed that I/O could become a major performance bottleneck in cluster-based Web servers. Adopting a large I/O buffer cache on separate server nodes is not a good performance-cost scheme and sometime infeasible because of the high price and poor reliability. Current native file systems do not work well for the poor performance. Specialized file systems suffer a poor portability problem. In this paper, we present a new light-weight, cooperative temporary file system (called CTFS) to boost I/O performance for cluster-based Web servers. CTFS has the following advantages: (a) consists of a peer-to-peer cooperative caching system using user-level communication technique to eliminate repeated file requests and conduct aggressive remote prefetch; (b) runs in the user space to achieve a good portability; and (c) organizes a group of files with good associated access locality together to form a cluster unit on disk and thereby providing a sustained high I/O performance without degradation. Comprehensive trace-driven simulation experiments show that CTFS achieves up to a 37% better entire system throughput and reduces up to 47% total disk I/O latency than those in asynchronous FFS for a 64 node cluster-based Web server.