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Help with understanding throughput of pcie and hard drives (self.selfhosted)

submitted 1 year ago* (last edited 1 year ago) by a_fancy_kiwi to c/selfhosted

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I've been interested in building a DIY NAS out of an SBC for a while now. Not as my main NAS but as a backup I can store offsite at a friend or relative's house. I know any old x86 box will probably do better, this project is just for the fun of it.

The Orange Pi 5 looks pretty decent with its RK3588 chip and M.2 PCIe 3.0 x4 connector. I've seen some adapters that can turn that M.2 slot into a few SATA ports or even a full x16 slot which might let me use an HBA.

Anyway, my question is, assuming the CPU isn't a bottle neck, how do I figure out what kind of throughput this setup could theoretically give me?

After a few google searches:

PCIe Gen 3 x4 should give me 4 GB/s throughput
that M.2 to SATA adapter claims 6 ~~GB/s~~ Gb/s throughput
a single 7200rpm hard drive should give about 80-160MB/s throughput

My guess is that ultimately, I'm limited by that 4GB/s throughput on the PCIe Gen 3 x4 slot but since I'm using hard drives, I'd never get close to saturating that bandwidth. Even if I was using 4 hard drives in a RAID 0 config (which I wouldn't do), I still wouldn't come close. Am I understanding that correctly; is it really that simple?

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[–] [email protected] 7 points 1 year ago* (last edited 1 year ago)

Actually...for a NAS, your network link is your limit.

You could have 4xPCIe5 M.2's in full-raid, saturating your bus w/64Gb/s of glory, but if you are on 1Gb/s wifi, that's what you'll actually get.

Still, would be fun to ssh in and dupe 1TB in seconds, just for the giggles. Do it for the fun!

Remember, it is almost always cheaper and fast enough to use a Thunderbolt / high-speed USB4/40Gbs flash drive for a quick backup.