Journaling deduplication with invalidation scheme for flash storage-based smart systems

Transaction support for filesystems has become a common feature in modern operating systems where data atomicity is achieved by writing transactions to the log region in advance. The logging mechanism is appropriate for flash storage devices due to the inherent nature of flash memory. However, the logging schemes inherently create multiple copies of data, leading to a decrease in the bandwidth of storage systems. In this paper, we present a simple and efficient invalidation scheme for multiple copies of data in a common journaling module. We identify two types of duplications, one in which there is an explicit duplication of the journal region and original region with the same data, and the other in which there is an implicit duplication of transaction commit operations. The invalidation of duplicated data reduces internal write and erase operations and garbage collection overhead for flash devices, which would otherwise increases external I/O bandwidth. Experimental results show that the overall performance improves roughly from 5% to 35% with the invalidation scheme for journal transactions.