On Wed, Jun 17, 2020 at 12:15 PM Albretch Mueller <lbrt...@gmail.com> wrote: > > HDDs have their internal caching mechanism and I have heard that the > Linux kernel uses RAM very effitiently, but to my understanding RAM > being only 3-4 times faster doesn't make much sense, so I may be doing > or understanding something not entirely right.
I suggest that you google a bit on how to do fileystem benchmarks first, then try it and report back if something is still odd. There are many ways but "dd" is not the way unless you really dig through the sync flags and understand what they do. I normally use "fio" but it's not very friendly (so it suits me). However, I just recently put a fast NVMe SSD in an older server with (lots) of DDR3 ECC RAM. The RAM bandwidth for one node/CPU is about 10-12 GB/s, and the SSD bandwidth is nearing 2 GB/s for most loads. That's getting close to your figures!
