Improving Data Consistency for Mobile File Access Using Isolation-Only Transactions

Disconnected operation based on optimistic replication has been demonstrated as an effective technique enabling mobile computers to access shared data in distributed file systems. To guard against inconsistencies resulted from partitioned data sharing, past research has focused on detecting and resolving write/write conflicts. However, experience shows that undetected read/write conflicts pose a subtle but serious threat to data integrity in mobile file access. Solving this problem is critical for the future success of mobile computing. This dissertation shows that isolation-only transaction (IOT), an upward compatible transaction mechanism for the Unix File System, is a viable solution to this problem. The central idea of the IOT model is imposing serializability-based isolation requirements on partitioned transaction executions. Transactions executed on a disconnected client stay in a tentative state until the client regains connection to relevant servers. They are committed to the s..