Optimising disk hardware for Unraid

I don't know if this has been covered before but I have been optimising my system from a hardware point of view to wring the most speed out of my array and thought I'd share what I did for the smaller scale users who might be interested. No software changes are necessary.

When using the on-board disk controller on a PC motherboard, all the drives are sharing the same bus so Unraid can't write to the parity disk and an array disk at the same time and has to do them sequentially. 4 port PCIe SATA controller boards are dirt cheap and are plug-and-play so if you get one and dedicate it to the parity disk, it will let Unraid write to both disks simultaneously and speed up the array quite a bit.

Don't add a second drive to that controller as it slows down transfers like before, but with the low cost of the controller boards it's no problem to sacrifice the other three ports and add a third controller for expansion if you need it.

Use the fastest disk you have for the parity disk, it makes a difference. I just replaced my WD 12TB parity disk with a WD 18TB drive and the rebuild is flying - 1GB/s read, 150MB/s write with a 72TB + parity array!

The array disks should use the motherboard ports and if you want to take this to max., separating slower and faster disks to different controllers will also make a small difference.

I hope this helps you.

Edited December 7, 2025Dec 7 by SimonP
Added section about using a fast parity disk