JUCS - Journal of Universal Computer Science 26(1): 89-106, doi: 10.3897/jucs.2020.006
Scalable Distributed Metadata Server Based on Nonblocking Transactions
expand article infoKohei Hiraga, Osamu Tatebe§, Hideyuki Kawashima
‡ Keio University, Kanagawa, Japan§ University of Tsukuba, Ibaraki, Japan
Open Access
Metadata performance scalability is critically important in high-performance computing when accessing many small files from millions of clients. This paper proposes a design of a scalable distributed metadata server, PPMDS, for parallel file systems using multiple key-value servers. In PPMDS, hierarchical namespace of a file system is efficiently managed by multiple servers. Multiple entries can be atomically updated using a nonblocking distributed transaction based on an algorithm of dynamic software transactional memory. This paper also proposes optimizations to further improve the metadata performance by introducing a server-side transaction processing, multiple readers, and a shared lock mode, which reduce the number of remote procedure calls and prevent unnecessary blocking. Performance evaluation shows the scalable performance up to 3 servers, and achieves 62,000 operations per second, which is 2.58x performance improvement compared to a single metadata performance.
distributed metadata server, nonblocking distributed transaction, parallel file system