Please keep in mind that in this situation the GUID will be provided by the adapter.

There are situations where it will not work

• If the GUID is generic, it might not work if it has already have been registered by someone else.

• if this GUID has been blacklisted

• if the adaptor has no GUID

https://docs.unraid.net/unraid-os/using-unraid-to/manage-storage/array/array-health-and-maintenance/#license-issues

i.e. does the adapter really provide a unique GUID or does the manufacturer re-use GUIDs. If multiple people use this hardware and end up with the same GUID it will result in the GUID being blacklisted.

3 hours ago, PlutoAQ said:

So, the procedure I followed, without even knowing what I was doing, was as follows:

I confess that I wasn't trying to boot from disk instead of USB, and that this was a discovery I made by accident.

That's been common knowledge for years, the problem is nobody can guarantee a particular adapter will work. These things are so generic and interchangeable that even if you buy one now and it's fine someone else buying from the same listing a couple months later may get one with no GUID because the seller changed the actual product they sell, use one with a different chip etc.

Edited December 14, 2025Dec 14 by Kilrah

So, I received the M2 NGFF to USB3 adapter, and I immediately wanted to test it, even though it wasn't licensed this time... just to see if the unRAID system would boot correctly and/or faster.

I have to say I was a little disappointed, because even though the PC port is USB3 and the adapter is also USB3, I didn't notice a significant increase in performance (neither in boot times nor in system shutdown times). Everything seems pretty much the same.

Perhaps because the unRAID system has some mechanism that prevents it from fully exploiting the USB3 protocol?

At this point I retrace my steps and... for my unRAID system made with a (recovered) Lenovo TS140 Server PC with 16 GB of RAM and 5 Sata ports on board (which I will increase in the future with a PCI Sata controller) I decided to use a small (I'm talking about size) USB pendrive, so I don't have the bulk of the M2-USB adapter and the USB pendrive won't protrude much from the case.

32 minutes ago, PlutoAQ said:

I have to say I was a little disappointed, because even though the PC port is USB3 and the adapter is also USB3, I didn't notice a significant increase in performance (neither in boot times nor in system shutdown times). Everything seems pretty much the same.

This is normal. You might gain a few seconds during boot in the time to load the bz* type files but the gain is very small. During normal running the system is running from RAM and therefore not constrained by the boot drive performance. That is one of the reasons why it is often recommended that if you can use a USB2 flash drive instead of a USB3 one as the performance gain is relatively small, and USB2 is far less prone to failure. The only real reason for wanting to boot from SSD is that it might be less prone to failure than a flash drive.

On 2/23/2024 at 5:06 AM, etegration said:

2024 - time to let us decide how we want to boot off a ssd or even NVME and run the OS from ram please. thumbdrives are totally useless and so unreliable. 

My USB-Stick is from 2012 - still in use and working 👍

Edited January 8Jan 8 by Zonediver

My drive was from 2015 only changed as too small. Internal boot is planned for 7.3

Very interesting... but after all the tests I have done, after everything I have read online (and not only on this forum), I have come to the conclusion (my very personal idea, of course) that it is better to have the boot device (and therefore the entire unRAID system) on a USB stick.

First, because you don't go and occupy a Sata port; second, because if the hardware fails, you just need to move the USB stick to the new hardware and everything starts again.