Global Wear Leveling can calculate the remaining P/E cycles of each block, and write on a top-priority basis new data to blocks with fewer erasing times. By controlling the number of erasing and writing of each block on average, the excessive erasing and writing and premature loss in some blocks of NAND Flash can be avoided so that the durability and stability of the SSD can be improved.
There is an upper limit on the number of P/E Cycle of NAND Flash blocks. If a single block is continuously written and erased, the said block will be excessively worn out, resulting in slower reading and writing speed. In severe cases, it may even be damaged with bad blocks produced. Global Wear Leveling serves to make each NAND Flash block in the SSD be used evenly, to prevent data from being written or erased only in certain blocks, causing the SSD to be damaged early due to excessive bad blocks in the NAND Flash.