this post was submitted on 03 Aug 2025
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I tried to find a more applicable community to post this to but didn't find anything.

I recently set up a NAS/server on a Raspberry Pi 5 running Raspberry Pi OS (see my last post) and since then I've got everything installed into a 3D printed enclosure and I've got RAID set up (ZFS RAIDz1). Prior to setting up RAID, I could transfer files to/from the NAS at around 200MB/s, but now that RAID is seemingly working things are transferring at around 28-30 MB/s. I did a couple searches and found someone suggesting to disable sync ($ sudo zfs set sync=disabled zfspool). I tried that and it doesn't seem to have had any effect. Any suggestions are welcome but keep in mind that I barely know what I'm doing.

Edit: When I look at the SATA hat, the LEDs indicate that the drives are being written to for less than half a second and then there's a break of about 4 seconds where there's no writing going on.

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[–] HiTekRedNek@lemmy.world 8 points 1 week ago

When people talk about CPU limitations on the rPi, they aren't talking about just the actual processing portion of the machine. There are also a lot of other corners cut for basically all SBCs. Including bus width and throughput.

The problem is that when you use a software raid, like ZFS, or it's precursors, you are using far more than the CPU. You're also using the data bus between the CPU and the IO controller.

"CPU usage" indicators don't really tell you how active your data buses are, but how active your CPU is, in having to process information.

Basically, it's the difference between IO wait states, and CPU usage.

The Pi is absolutely a poor choice for input/output, period. Regardless of your "metrics" tell you, it's data bus simply does not have the bandwidth necessary to control several hard drives at once with any sort of real world usability.

You've wasted your money on an entire ecosystem by trying to make it do something it wasn't designed, nor has the capability, to do.