Transaction management for a distributed object storage system WAKASHI-design, implementation and performance

This paper presents the transaction management in a high performance distributed object storage system WAKASHI. Unlike other systems that use centralized client/server architecture and other conventional buffer management for distributed persistent object management, WAKASHI is based on symmetric peer-peer architecture and employs memory-mapping and distributed shared virtual memory techniques. Several novel techniques of transaction management for WAKASHI are developed. First, a multi-threaded transaction manager offers “multi-threaded connection” so that data control and transaction operations can be performed in parallel manner. Secondly, a concurrency control mechanism supports transparent page-level locks to reduce the complexity of user programs and locking overhead. Thirdly, a “compact commit” method is proposed to minimize the communication cost by reducing the amount of data and the number of connections. Fourthly, a redo-only recovery method is implemented by “shadowed cache” method to minimize the logging cost, and to allow fast recovery and system restart. Moreover, the system offers “hierarchical” control to support nested transactions. A performance evaluation by the OO7 benchmark is presented