SSDs are fast storage devices that have come down in price a lot over the years.
Before we discuss the different types of flash, it will be helpful to cover three more acronyms.
These respectively offer 150, 300, 600, and 1200 TBW warranties.
As the size of the drive doubles, so does the warrantied amount of data written to the drive.
This comes out to 600 full drive writes or 600 TDW covered under warranty.
The final acronym is DRPD or Drive Writes Per Day.
At the 250GB capacity thats only 83GB a day, for five years.
At the 2TB capacity thats 666GB, every day, for five years.
It stores a single binary bit of data in each memory cell.
Those issues have now been resolved with much faster connectors, better drivers, and better wear levelling technology.
SLC is the fastest pop in of flash memory and has the longest lifespan.
It is, however, the most expensive, and is basically not used anymore.
MLC
MLC stands for Multi-Level Cell.
This pop in of flash memory stores two bits of data per flash memory cell.
Additionally, the overall lifespan of the memory cell is reduced.
TLC
TLC stands for Triple-Level Cell.
It is the current standard memory configuration for flash memory in SSDs.
Thats triple the storage density of SLC and 50% higher density compared to MLC.
Again, TLC comes with the same drawbacks and mitigating factors as well as a few new improvements.
It suffers from a lower life span than MLC flash, but improved wear levelling helps to manage this.
TLC is also slower to read and write to.
Read speeds arent an issue, even with modern high-speed storage mechanisms, they can still saturate the bandwidth.
The data is then offloaded to the TLC as fast as possible to free up space.
Note: The Samsung 980 Pro, for which we provided stats above, uses TLC flash.
QLC
QLC stands for Quad-Level Cell.
There are a relatively small number of QLC SSDs on the market.
They also come with even more severe speed penalties when the SLC cache is exhausted.
The technology will continue to mature and over time may replace TLC as the standard storage method.
It comes in 1, 2, 4, and 8TB capacities rather than topping out at 2TB.
The longevity decrease can be fairly easily seen in high-end drives that are as closely comparable as possible.
With more levels per cell, you get a lower TBW and TDW rating.
Accordingly, the warranty period may be reduced to keep the DRPD rating up at marketable values.
PLC
As you might be able to guess, PLC stands for Penta-Level Cell.
It stores five bits of data per cell.
There are no commercially available PLC SSDs currently as this technology is still in development.
It will offer the same pros and cons.
Increased storage density and reduced price, at the cost of reduced lifespan and speeds.
Memory manufacturers are also talking about possibilities beyond PLC including storing seven levels per cell.
Each memory cell is a single transistor.
The main difference is in how theyre controlled.
TLC is currently the way to go unless you really need an 8TB SSD.
Often the SLC cache may be mentioned, but not have its capacity advertised.
Its important to find trustable and detailed reviews that check for this if high-performance is what youre aiming for.
