HV-recovery: A high efficient recovery technique for flash-based database

Flash memory, as a new kind of data storage media, has a lot of attractive characteristics when compared with Hard Drive Disk (HDD) such as fast access speed, shock resistance, power saving, lighter form and low noise. Therefore flash memory is considered as the main storage device instead of disk in the next generation. However, traditional disk-based database can't take full advantage of high I/O performance of flash memory if we transfer it to flash memory without modification. The main reason is flash memory embraces different access characteristics with HDD. As for recovery, the situation becomes more serious because the out-of-place update model and erase-before-rewrite of flash memory lead to high cost of large quantity of minor random writes during the course of recovery. This paper proposes a recovery method, HV-recovery, to improve the performance of undo. HV-recovery makes use of the history versions of data which is naturally emerged in flash memory due to the out-of-place update. Experimental results on Oracle Berkeley DB show that the HV-recovery outperforms traditional recovery in 2×~8×. The results demonstrate the high efficiency of the method.