VirtualGC: Enabling Erase-free Garbage Collection to Upgrade the Performance of Rewritable SLC NAND Flash Memory

Since 3D NAND flash memory could provide more reliable storage than a 2D planar flash memory by relaxing the design rule of a memory cell, a kind of brand new programming technique, namely erase-free scheme, has been proposed to further enhance the endurance of a 3D SLC NAND flash memory. The erase-free scheme brings tons of benefits to flash memory performance and endurance. For example, the erase-free scheme could reclaim invalid (page) space without physically erasing a flash block. However, current flash management designs could not fully exploit the benefits of the erase-free scheme. With the considerations of the features of the erase-free scheme, this paper is the first work to propose a novel flash management design, namely VirtualGC strategy, to deal with the erase-free garbage collection process. By taking the advantages of the erase-free scheme, the proposed strategy reduces the overhead of copying live pages so as to increase flash memory performance. The results show that the proposed strategy significantly improves the performance of rewritable 3D flash memory drives.