In the era of data explosion, people have more and more demand for SSD capacity, and storage capacity is facing unprecedented challenges. Following the mainstream of TLC SSDs, QLC flash memory is also on the scene, meeting users' high-density capacity. Demand.
NAND flash memory has SLC, MLC and TLC, and now there are more QLC
Many people know that NAND flash has SLC, MLC and TLC, and now there are more QLC flash, so how much difference between them?
SLC=Single-Level Cell, each Cell unit stores 1 bit of information, that is, only 0 and 1 voltage changes, the structure is simple, and the voltage control is also fast. The characteristic is that the life is long, the performance is strong, and the P/E life is Between 10,000 and 100,000 times, but the disadvantage is low capacity, high cost, after all, a Cell unit can only store 1 bit of information.
MLC=Multi-Level Cell, which actually corresponds to the SLC. The NAND flash memory outside the SLC is of the MLC type. The MLC is often referred to as the 2bit MLC. Each cell unit stores 2 bits of information and has a voltage of 000. There are four variations of 01, 10, and 11, so it requires more complicated voltage control than SLC, and the pressurization process takes longer, which means that the write performance is reduced, and the reliability is also reduced. The P/E life is different. The process ranged from 3,000 to 5,000, and some were even lower.
TLC = Trinary-Level Cell, ie 3bit/cell, each unit can store 1/2 more data than MLC, a total of eight charging values, 111, 110, 101, 011, 010, 001, 000.
The biggest feature is that the speed is slow and the life is short, about 500-1000 erasing life, but the price is the lowest of the three. Due to the cost of the price, it is widely used in consumer SSD.
QLC = Quad-Level Cell, we know that TLC flash memory stores 3 bits of charge per Cell unit, there are 8 states, QLC flash memory stores 4 bit charge, there are 16 states, capacity increases by 33%, but write Performance, P / E life will be reduced again.
From the above introduction, QLC flash memory has a lower read/write speed and reliability than other three types of flash memory. So, why is QLC favored by many vendors?
Nowadays, as more and more data is being stored, storage disks will face unprecedented challenges from big data. At this time, large-capacity products are needed for storage. Therefore, SSDs need cheaper flash memory solutions. Let the large-capacity solid state drive cost less.
Although the current life and performance are inevitable shortcomings of QLC flash memory, with the improvement and development of the SSD process, its shortcomings have been well solved. For example, Intel's QLC flash memory directly uses 3D NAND technology, P/E lifetime. It has reached 1000 times, and it does not lose the current 3D TLC flash memory.
The big capacity advantage can't be ignored, QLC is the trend of the times
In the face of the global demand for flash memory, the high price of SSD, the emergence of QLC flash memory, its cheaper cost and greater capacity advantage can not be ignored by manufacturers and consumers. In short, with the continuous development and maturity of technology, QLC was Wide recognition is also a matter of time.
