Oct 2022 Knowledge Sharing Article: QLC FLASH: THE LATEST ADVANCEMENT IN STORAGE

This article will address the advantages of Quad Level Cells (QLC) and try to understand under which workloads they will work best. To understand all of it, let’s first learn a little about NAND (Not AND) in general.
Unlike other types of storage, programming data to a NAND cell requires erasing the old data in the cell before writing new data on it, referred to as the Program/Erase (or P/E) cycle.
How is the whole process carried out? It is done by sending electrons through an insulator back and forth by applying a voltage to it. The location and quantity of these electrons sent will determine the current flow between the voltage threshold (source and sink), which in turn will determine how much data (Binary: 0s and 1s) has been written/programmed in the NAND cell.
However, this procedure may have a drawback in certain situations. When the number of electrons will be more than what the insulator can take, it will have difficulty keeping the data in the correct location that we wanted to program it on. This will lead to one of the two scenarios; has the data been programmed to the correct location, or has it migrated somewhere else. To minimize this drawback and such scenarios, we have different types of NAND flash.

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