A dual-time vector clock based synchronization mechanism for key-value data in the SILENUS file system

The SILENUS federated file system was developed by the SORCER research group at Texas Tech University. The federated file system with its dynamic nature does not require any configuration by the end users and system administrators. The SILENUS file system provides support for disconnected operation. To support disconnected operation a relevant synchronization mechanism is needed. This mechanism must detect and order events properly. It must detect also possible conflicts and resolve these in a consistent manner. This paper describes the new synchronization mechanism needed for providing data consistency. It introduces dual-time vector clocks to order events and detect conflicts. A conflict resolution algorithm is defined that does not require user interactions. It introduces the switchback problem and how it can be avoided. The synchronization mechanisms presented in this paper can be adapted to synchronize any key-value based data in any distributed system.