Hello all. I'm considering switching to Unraid from ZimaOS. My primary reason (among a few reasons), is the hope that Unraid treats external drives differently than my current OS.

I run my server from an Intel NUC mini PC. In these devices there is not a lot of room for drives. The device only has room for a single m.2 drive and single 2.5" drive. Most of my data is stored on a 4TB external Seagate drive, and two 3.5" HDDs. The two HDDs are connected via USB with a 2 bay USB dock.

On my current OS, these drives are treated as external drives (which I understand, because that's exactly what they are). I would like the option for parity on these drives. Unfortunately, I don't think this is going to change in future updates of my current OS. I know this is by design, and possibly due to some technical limitation that is probably way over my head.

I am curious as to whether this is true with Unraid as well. With Unraid are you able to use a USB connected drive as a parity drive? Furthermore, is it possible to configure an external drive(s) in your storage pool in Unraid?

Thanks in advance, and sorry for the possibly dumb question. I did search the forum for "USB drive" and "external drive" and did not find any topics in a similar vein.

4 hours ago, wolfioso said:

With Unraid are you able to use a USB connected drive as a parity drive?

You are, but it's not recommended to use USB for array or pool devices, since it has a tendency to drop drives and is bad at error handling in general, but some users use them without major issues. It will depend in part on the quality of the USB bridges used.

That's understandable. I get that it's not optimal, I just wanted to confirm that it's an option that Unraid allows.

You simply assign the USB drive to an array slot, either parity slot or an array slot, and start the array.

Do be aware, if the disk ID changes, you will need to likely rebuild the data onto the disk. Parity can also become invalidated.

Edited December 12, 2025Dec 12 by MowMdown

13 hours ago, MowMdown said:

You simply assign the USB drive to an array slot, either parity slot or an array slot, and start the array.

Do be aware, if the disk ID changes, you will need to likely rebuild the data onto the disk. Parity can also become invalidated.

Thanks, this is a helpful warning. I am assuming on a single external disk this is less of an issue? I also have two HDDs connected via a single USB Orico docking bay, I would think this would happen every so often on that device since the bay itself doing the assignment. If it helps at all, my orico bay drives are only used for backups and I honestly wouldn't even miss having those drives on my NAS. My external Seagate drive stores all my media data though and that's the drive I access the most. Having to reconfigure this often would be a bit of a headache.

I just got Unraid going on a spare prebuilt Dell (finally) which has several SATA connections. I am going to see how much power this device pulls for a while under my normal workload and see if it makes economic sense to switch my HDDs over to the Dell for Jellyfin and run all my 24/7 containers on my NUC. To make this make a bit more sense I'll have to find a way to set up my Dell to wake-on-lan from remote locations.

I'm rambling, thanks for your help.