this post was submitted on 25 Sep 2023
26 points (93.3% liked)

Selfhosted

40415 readers
321 users here now

A place to share alternatives to popular online services that can be self-hosted without giving up privacy or locking you into a service you don't control.

Rules:

  1. Be civil: we're here to support and learn from one another. Insults won't be tolerated. Flame wars are frowned upon.

  2. No spam posting.

  3. Posts have to be centered around self-hosting. There are other communities for discussing hardware or home computing. If it's not obvious why your post topic revolves around selfhosting, please include details to make it clear.

  4. Don't duplicate the full text of your blog or github here. Just post the link for folks to click.

  5. Submission headline should match the article title (don’t cherry-pick information from the title to fit your agenda).

  6. No trolling.

Resources:

Any issues on the community? Report it using the report flag.

Questions? DM the mods!

founded 2 years ago
MODERATORS
ruud
Loki
CannaVet
devve
HybridSarcasm
[email protected]
26
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
10 comments fedilink hide all child comments
 

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?

you are viewing a single comment's thread
view the rest of the comments
[–] [email protected] 2 points 1 year ago (1 children)

Yeah but you're not going to saturate each SATA port with your harddrives, which will be closer to 2 gbps max. The PCIE connector only needs to worry about what actually goes across it. I imagine that card is built to spec with the situation you're describing in mind, but for more practical purposes I think it shouldn't be a problem to have even more slots?

[–] a_fancy_kiwi 1 points 1 year ago

Oh that’s right, I didn’t take into account the speed of the hard drives. Sweet