Samsung has announced a pair of high-capacity SSDs based on its 3D NAND (also known as V-NAND) technology — the 850 EVO and the 850 Pro. Specs on the drives are similar to the smaller capacity products that have already launched, but the drive densities have skyrocketed. The 2TB 850 Pro contains 128 individual 32-layer Flash ICs (128Gb capacity per IC, or 16GB). Samsung also upgraded the MHX NAND controller to handle 2TB arrays, and boosted the on-drive cache to 16Gb (2GB) of LPDDR3. Take the original 850 Pro and 850 Evo and scale them up, and this is what you get.
Performance specs on the two drives haven’t been disclosed yet, but we’d expect the 850 Pro to be moderately faster than the 850 EVO, which uses TLC NAND and an SLC cache buffer to boost overall performance. Readers may be concerned about the 850 EVO suffering from some of the same issues that have plagued the original 840 EVO, but we’ve seen no reports that link the 850 EVO to similar performance degradation — and there’s reason to think it may not be an issue.
Samsung’s vertical NAND is built on 40nm technology rather than the 19nm NAND that Samsung used on the 840 EVO. While lower process nodes are typically thought of as being unilaterally good for semiconductor design, that’s not the case for NAND flash, which suffers lower data retention and decreased durability as the process node shrinks. In this case, the 850 EVO likely benefits from being built on higher process technology while still offering the benefits of vertical design. We’ve covered Samsung’s V-NAND, the 850 Pro, and 850 EVO in the past, so readers wanting more information on these topics are advised to refer to those articles.
The one difference we do know about as of this writing is the warranty period on the two drives and the total write guarantee is quite different. Samsung guarantees the 850 EVO to 150TB written, whereas the 850 Pro is guaranteed for 10 years or 300TB written. Previous testing has confirmed that drive manufacturers tend to be extremely conservative about the maximum write capacity of their drives; even TLC drives are often capable of writing 2-3x more data than the manufacturer specifies.
Pricing for the new drives is reportedly set at $800 for the 2TB 850 EVO and $1000 for the 2TB 850 Pro. while still a huge amount of money in absolute terms, these figures show that the 850 Pro has come down to 50 cents per GB — a huge advance compared to a few years ago, when $1 per GB was common, even on budget drives. We don’t expect to see SSDs fall to HDD per-GB pricing in the near-term future, but the gap between the two standards should continue to decrease, making larger capacity SSDs more affordable in the process.
