Q What’s the difference between SLC, MLC and TLC?

A In terms or write performance, durability and price SLC > MLC > TLC.

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SLC, MLC and TLC refer to the structure of flash memory cells and how many bits each cell can store. SLC stands for single-level cell which stores one bit, MLC stands for multi-level cell which stores two bits and TLC stands for triple level cells. A bit is a 0 or 1 and so 8 billion cells are required for one gigabyte of SLC flash storage. As the number of bit levels within each cell increases, fewer cells are required to store the same data so there is a decrease in manufacturing cost per MB. SLC flash is also more durable and can reach up to 100,000 program/erase cycles compared to up 10,000 cycles for MLC and up to 5,000 cycles for TLC devices.

TLC and MLC devices are consumer grade products. Despite the lower durability of TLC flash, it is absolutely sufficient for use as a bootable disk which infrequently changes. A consumer may achieve better longevity and therefore better value for money from a larger TLC device than a smaller MLC due to how the memory would deteriorate over a greater number of cells.

SLC flash devices are generally only used at enterprise level and carry a premium in return for increased endurance, faster write speeds and lower power consumption. eMLC stands for enterprise multi-level cell and has a two bit level structure. It has enhanced durability (up to 30,000 program/erase cycles) at a higher price than comparable MLC.