On Fri, Nov 12, 2021 at 2:56 PM Rich Freeman <ri...@gentoo.org> wrote: > > On Wed, Nov 10, 2021 at 11:06 PM Mark Knecht <markkne...@gmail.com> wrote: > > > > > > Not a recommendation precisely but there's a guy on YouTube named Jeff > > Geerling that's doing a lot of that sort of thing using a Raspberry Pi and > > multiple SATA drives. I've just built my first RP4 box aimed at > > astrophotography and I'm pretty impressed with how well the Pi works. My > > next project will likely be some sort of NAS box using a second Pi4 with an > > M.2 system drive. > > > > I run LizardFS and at this point Pi4s are my preferred hardware for > storage nodes. However, I don't deal with much IOPS. I tend to use > USB3 hard drives for convenience/cost. Really though SATA on a Pi4 > wouldn't be super-ideal anyway due to the lack of PCIe (I think it > lacks it at least). You can find ARM SBCs that have PCIe capable of > handling an HBA which are probably better if you want a bunch of SATA > drives, though those have their downsides. If you're serious about > IOPS I'm not sure anything cheap will do the trick. > > I would definitely avoid Pi2/3 for this due to the combo of 100MBps > networking and USB2 and a lot of the IO goes through USB2 in the first > place. It is just not a very good setup for IO at all, and there are > much better alternatives. The Pi4 though is pretty solid as long as > you don't mind USB3 (and it has two hosts so you can basically run 4 > spinning disks all-out without a performance hit until you get to the > network at least). > > Gigabit network is its own bottleneck for any kind of storage. I'm > too cheap to try to use anything better, but anybody doing serious DFS > is going to want 10Gbps, or often dual 10Gbps. > > -- > Rich >
My understanding (from Geerling's video as well as looking at the Pi Compute Module manual) is that the standard RP4 has PCI express but it's hooked to the USB3 chip. In the case of the Pi 4 Compute module the PCI express is available to be used by the motherboard that you plug the compute module into. https://datasheets.raspberrypi.com/cm4/cm4-datasheet.pdf The NAS box Geering was demoing in this video: https://www.youtube.com/watch?v=YtdVotS3018&t=1023s is a kickstarter project https://pibox.io/ which I don't think is available yet but will run in the $250 range without the drives. It appears that the motherboard they designed takes the PCIe to a card with a PCIe-to-SATA controller which is how you get better performance. This designed is GB Ethernet which is probably the actual performance bottleneck. Cheers, Mark
