They don't stop at 4TB though... consumer SATA drives go up to 16TB. And I've heard there are even larger enterprise drives. https://www.amazon.com/dp/B09FJFMQBB
From the article I linked: "...capacities larger than that only available from a few specialty vendors at eye-watering prices"
From what I can tell, this was true when it was written, but has changed since with the Samsung QVO 8TB SATA only at a roughly 25% markup compared to a 8TB QLC M2 2280 drive. When I searched last winter it was 2-4x expensive as soon as you crossed the 4TB mark, with 4TB and under being similarly priced between SATA and nvme drives.
That's the reality of low-volume products, they're expensive. Most people dropping that much cash on NAND will just drop the cash to plug it into something that can access it quickly. If you want big slow storage for cheap, just get a spinning disk.
Random IOPS through a SATA interface is orders of magnitude faster on NAND vs a spinning disk. A SATA SSD and a spinning disk might as well be two completely different categories of device for any non-sequential workload.
You can do it with PCIE switches, but you shouldn't. If you need 16 NVME drives, you need to put them in an appropriate host system.
To properly design a computing solution, first you define the requirements, and then you select components with specifications that will fulfill your requirements.
If you try to work backwards, you are destined for failure. Dropping big cash on 16 high-capacity SSDs just to ham-jam them in an old system is a really really dumb idea, especially if you're concerned about IOPS.
Are you not aware that the region between "saturating 64 PCIe channels" and "spinning disks" contains a huge space of performance, much of which might be acceptable?
