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 offer 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 on 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, as well.