A control scheme for eliminating garbage collection during highspeed analysis of big-graph data stored in NAND flash memory

A new control scheme for eliminating garbage collection during high-speed analysis of big-graph data stored in NAND flash memory is proposed and evaluated. During big-graph analysis, intermediate results of the analysis stored in NAND flash memory are updated repeatedly. When a conventional control scheme is applied, excessive data copying, called “garbage collection,” occurs because overwriting data to NAND flash memory is prohibited. Such excessive data copying degrades the performance of big-graph analysis. When the proposed control scheme is applied, the controller of NAND flash memory writes the intermediate results which are updated at the same time to the same block of NAND flash memory, and the excessive data copying is eliminated completely because all the data in the block can be erased at the same time before the intermediate results are updated. As a result, the proposed control scheme shortens analysis time by 88% and increases analysis speed for big graphs 8.7 times. These results show that the proposed control scheme enables high-speed analysis of big graphs.