Flash memory has had a huge impact on the way we use computers. Flash, which powers everything from thumb drives, SD cards and the memory chip in your phone up to high performance SSDs in computers and data centers, stores information in a network of specialized transistors, and has big advantages over traditional hard drives. Flash is lightweight, has no moving parts, and can transfer data many times faster than a hard drive, and with lower latency.
But flash has struggled to keep up with our exploding demand for data. SLC, the fastest, most robust type of flash, can only one store one bit of data in each transistor, called a “cell”, meaning a terabyte of SLC storage requires literally a trillion transistors. To work around this, companies developed MLC and TLC flash, which store 2 and 3 bits of data per transistor. This massively increases flash drives’ capacity, but it comes at a cost. MLC and TLC drives are slower, and will wear out faster than SLC flash. Still, by adding some extra space or “over-provisioning”, MLC and TLC drives can last a long time, and smart cache systems boost read and write speeds for most workloads.