Flash Module with DRAM Buffer
The purpose of designing an additional DRAM chip into the flash module is to increase both performance and endurance.
A DRAM chip in a flash module has exactly the same function as a cache in a hard disk. Whilst the flash module is in operation the controller throws small data into the DRAM chip for immediate responses; the DRAM chip acts as a directory that assists the controller to allocate data to the assigned positions. Therefore it shortens the response time and increases the performance.
Comparing Flash Storage to DRAM, DRAM does not have any limitation of program/erase cycles, whereas Flash Storage does. Every time when the controller tries to program a sector of data into Flash Storage, it needs to erase a whole block of Flash before re-programming it. However with the DRAM buffer small data can be collected to a certain amount before delivering to the Flash Storage which reduces the program/erase times to the flash chips, and therefore increases the endurance.