We reported here about Samsung’s launch of the new 840 SSD series and we promised we’d be back with more technical details on the new drives as the company has been quite shy about them.
The new drives use TLC NAND
flash cells instead of the popular MLC NAND. In fact, the 840 Pro series still uses MLC NAND, and the more affordable basic 840 SSDs use TLC.
TLC is short for triple level cell and it basically means that each NAND cell is able to record three bits of information while MLC is only able to record two bits.
Users that are hoping for a quick price reduction are going to be somewhat disappointed, as TLC NAND has serious durability problems when compared with the already durability-challenged MLC NAND
The company has not made public any program/erase or P/E cycles ratings for the TLC-based SSDs, but it is widely known that TLC will have modest reliability when compared to MLC.
To combat this issue, the company has invested in other technologies that will lessen the wear and tear of the SSD. However, these generally cost money that will reflect in the final price of the drive.
It’s also important to note that the new flash is manufactured in 21nm technology, which means that there is also a wafer-based cost reduction that must be taken into account.
Moreover, smaller NAND cells will also negatively affect durability even further, so Samsung’s NAND protection technologies have lots of work to do considering the combined durability problems that the move from MLC to TLC and 27nm to 21nm pose.
One mention Samsung
made is that TLC NAND is reportedly 50% slower than MLC flash and, therefore, users expecting a performance hike will likely be disappointed.
On the other hand, the company assured the journalists, taking part at the Seoul launch, that the new TLC drives are more reliable than many MLC SSDs on the market which, in our opinion, is not that reassuring.
The MDX controller uses a 3-core design and, compared with MCX-powered SSDs from the company, is quite a bit faster.
The IOPS numbers are doubled when writing is concerned and read IOPS ratings now reach the 100,000 mark.
Overall, performance has increased, as sequential read speed went up from 520 MB/s (Samsung 830 SSD
) to 540 MB/s for the 840 and the 840 Pro.
The write speed went from 400 MB/s to 450 MB/s in the 840 Pro with the mention that the TLC-based 840 is rated at only 330 MB/s.
The IOPS numbers are clearly higher, as even the “slow” 840 is rated at 98,000 IOPS when reading and 70,000 IOPS when writing versus the 830 SSD that only reaches 80,000 IOPS when reading and 36,000 IOPS when writing.