Distributed Checkpointing for Globally Consistent States of Databases

The goal of checkpointing in database management systems is to save database states on a separate secure device so that the database can be recovered when errors and failures occur. Recently, the possibility of having a checkpointing mechanism which does not interfere with the transaction processing has been studied [4], (7], Users are allowed to submit transactions while the checkpointing is in progress, and the transactions are performed in the system concurrently with the checkpointing process. This property of noninterference is highly desirable to real-time applications, where restricting transaction activity during the checkpointing operation is in many cases not feasible. In this paper, a new algorithm for checkpointing in distributed database systems is proposed and its correctness is proved. The practicality of the algorithm is discussed by analyzing the extra workload and the robustness of it with respect to site failures.