20TB SSDs Are Still A Bit Rare
Once of the reasons you don’t see 20TB SSDs, either SATA or NVMe, is because the sticker shock could traumatize the weak of heart, especially if they are looking to pick up several of them to populate a NAS device. There is also the argument that disks of that size tend to be used for applications where speed is secondary to reliability. This is why there are series such as Seagate’s IronWolf Pro and Exos NAS drives, a consumer grade model and an enterprise grade respectively.
The drives are very similar, using conventional magnetic storage as opposed to shingled, though they are filled with helium to allow for such dense storage. The drives are rated for up to 285 MB/s of throughput, nowhere near the same class as SSDs but quite impressive for a HDD. The Exos offers better random write performance, which makes sense as an enterprise grade drive.
It is impressive to see drives of this capacity built on CMS, as opposed to shingled magnetic, HAMR or other new techniques which do not get along well in a NAS. Check out the full details of both drives over at TweakTown. While, neither drive appears for sale yet, but if you are shopping for something right away the 16TB versions of these drives seem to be on sale at the moment.