The fastest NVMe drives have the equivalent of no cache. Why?
Their entire NAND fabric is comprised of the faster type of NANDs.
Or to put it another way…
A nothing special NVMe drive could have 10% of its capacity made from SLC NANDs (and they call that 10% “cache”).
A high-end NVMe drive will have 100% of its capacity made from SLC NANDs.
Cache is useless for plotting. It gets filled quickly, and then the drive slows down to a crawl, because it is forced to write directly to its slow NAND cells.
I ran into this when I tested the Samsung T5 USB drive and the Samsung T7 USB drive.
The T5 blew away the T7.
The T7 is twice as fast as the T5, that is, until the T7 runs out of cache. The remaining storage area within the T7 is slow. Samsung is selling the T7 without issues, because nearly no one uses it for plotting or other huge write operations. So the T7 flies for the people that use it, because they never exceed its cache.
The T5, on the other hand, runs at full speed and never slows down, no matter how hard you hammer it and no matter how long you hammer it.
For plotting, you want a drive whose entire NAND structure is comprised of SLC or MLC fabric. I have no idea how to determine this, because the manufacturers do not make that information available.
EDIT:
I use the Samsung 2 TB 980 Pro for plotting.
It is fast, and appears to never slow down. I assumed that it had the same NAND fabric throughout its structure.
I just came across a review on tomshardware. Apparently the 980 Pro does employ a caching scheme, and the rest of the drive is TLC NAND.
But somehow Samsung designed its latest iteration of TLC fabric to be quite fast.
Its predecessor, the 970 Pro, appears to be 100 MLC fabric, and is touted as being superior to the 980 Pro. But the 970 Pro has a top capacity of 1 TB. And I suspect that the 980 Pro, due to its revised TLC fabric and updated controller might be faster at plotting vs the 970 Pro.
It has been a while since I used my plotting rig to process a single plot (I usually plot two at a time to two 980 Pro drives). But I believe that a single K34 plot took me 3½ - 4 hours via madmax.
Running two at a time averages out to 5¾ - 6 hours, via madmax.
So although the 980 Pro does slow down after its cache is full, the slow-down is minimal. Its remaining TLC cells are quite fast.
Other than data center grade NVMe drives (which I believe are a form factor that will not fit into a standard M.2 slot), I believe that the Samsung 2 TB 980 Pro is the fastest plotting drive for us mortals.