While other commenters have a point about initial downloads to cache and such for much better performance – it still isn’t fundamental ‘wrong’ and shouldn’t be THAT slow in a relatively modern system writing directly to the array.
My guess is that there’s something about the way your HDDs are hooked up which becomes a bottleneck when the system needs to read all the drives in parallel to compute parity.
Sometimes it’s as simple as ‘my PCIe drive controller is in the wrong slot on the motherboard, so limited to PCIe 2.0 1x lane speeds’, or that certain SATA headers on the motherboard go through an expansion chip (we used to call this the “south bridge”) rather than interfacing directly with the CPU/“north bridge”
While other commenters have a point about initial downloads to cache and such for much better performance – it still isn’t fundamental ‘wrong’ and shouldn’t be THAT slow in a relatively modern system writing directly to the array.
My guess is that there’s something about the way your HDDs are hooked up which becomes a bottleneck when the system needs to read all the drives in parallel to compute parity.
Sometimes it’s as simple as ‘my PCIe drive controller is in the wrong slot on the motherboard, so limited to PCIe 2.0 1x lane speeds’, or that certain SATA headers on the motherboard go through an expansion chip (we used to call this the “south bridge”) rather than interfacing directly with the CPU/“north bridge”
There’s an unraid disk speed testing plugin that can help narrow things down. I’d suggest you install and run this to at least rule out that problem: https://forums.unraid.net/topic/70636-diskspeed-hddssd-benchmarking-unraid-6-version-2107/