ST-CDP: Snapshots in TRAP for Continuous Data Protection

Continuous Data Protection (CDP) has become increasingly important as digitization continues. This paper presents a new architecture and an implementation of CDP in Linux kernel. The new architecture takes advantages of both traditional snapshot technology and recent Timely Recovery to Any Point-in-time (TRAP) architecture [CHECK END OF SENTENCE]. The idea is to periodically insert snapshots within the parity logs of changed data blocks in order to ensure fast and reliable data recovery in case of failures. A mathematical model is developed as a guide to designers to determine when and how to insert snapshots to optimize performance in terms of space usage and recovery time. Based on the mathematical model, we have designed and implemented a CDP module in the Linux system. Our implementation is at block level as a device driver that is capable of recovering data to any point-in-time in case of various failures. Extensive experiments have been carried out to show that the implementation is fairly robust and numerical results demonstrate that the implementation is efficient.