Differences Among SSD NAND Flash Memory: SLC/MLC/TLC

Before analyzing SSD, we need to figure out the anatomy of an SSD:

A. NAND Flash: This part is the location save your data, in blocks of non-volatile (does not require power to maintain data).

B. DDR Memory: Small amount of volatile memory (requires power to maintain data) used to save cache information for future access. Not available on all SSD.

C. Controller: The main connector between the NAND flash and your computer.

NAND Flash Memory is a newer and better storage media when comparing with traditional HDD. It is adapted with the non-volatile memory which can still save data even power off.

NAND flash memory is built up of many cells that holds bits and those bits are either turned on or off through an electric charge. The organization of the cells represents how the data stored on the SSD. The number of bits in those cells also determine the naming of the flash, for example Single Level Cell (SLC) flash contains a single bit in each cell.

Because the circuit board of the SSD has to fulfill the industrial standard, MLC doubles the  amount of bits per cell whereas TLC triples. And this opens up a trendy of high capacity SSD. And now, the manufactures are trying to minimize the production cost of storage of each bits of NAND flash and improve the capacity at the same time.

Single level cell, also called SLC, has the advantage of being the most accurate when reading or writing data. Besides, it has the longest life span over any other type of flash memory.

The read/write life cycle of SLC is expected to be between 90,000 and 100,000. This type of flash memory has done exceptionally well in the enterprise because of it’s life span, accuracy and overall performance. It is not so common in home computers with this type of NAND due to its high cost and low storage capacities.

Multiple Level Cell, short for MLC, stores 2 bits of data on one cell. The advantage is to lower the cost of manufacturing. As we all know, the cost in flash memory production is generally passed onto conumer in the end.

For consumer SSD, using MLC flash memory will be preferred for its lower costs. Although the read/write life is about 10 thousand time per cell, it is enough for normal use.

TLC flash stores 3 bits of data per cell and it is the cheapest form of flash to manufacture. The biggest disadvantage of TLC is that it is only suitable for consumer usage and not be able to meet the standards for industrial use. Read/write life cycles are considerably shorter at 3,000 to 5,000 cycles per cell.