I don’t understand what you are trying to say. If you can find a 16TB spinning disk that will work with a NUC, go for it. ROCK will not stop you.
There is no 8TB limit, why would we document it? There is no (reasonable) limit to the number of USB devices you can connect either, but the NUC boards do have a limit on USB ports. I’m not sure what you are asking for.
Sorry Danny but maybe I misinterpreted your “won’t support it” as to the greater than 8TB drives, and you meant something different re drive size (not just physical). So my apologies.
I have a Nucleus (acquired recently) so know its limitations re internal media. I’ve also run ROCK setups on NUC and other non NUC platforms - MOCK and used Windows and MAC options too over the V1.3-17 releases. Now I am suffering a spinning 13TB library on a W10 i7-7700 but hope to trim down that to get what I can’t find on Tidal/Qobuz on something SSD based in the future.
Whatever it is running on works great and life wouldn’t be the same without my enjoyment of Roon
This doesn’t apply to me because I have almost no music of my own, just curious. For someone with a NUC or Nucleus and a huge library of music files, could they install one large SSD internally and a second USB SSD and have two watched drives, with different music files, of course? For instance, could they purchase 2 - 8TB SSD’s and install one internally and one externally?
Yes but just remember that the internal is more of a physical size limitation and external you’re limited by the lack of USB ports (2) so if one is a DAC then you are left only 1 USB for a drive - then you need to think about where you put your backups in not on the external USB music drive.
Yes. That’s what I have present. Some music files on an internal 1TB SSD and the rest on a 4TB external HDD.
Hence my initial question about 8TB internal SSB drives to rationalise all the files on to one drive.
From what Danny’s saying, there’s nothing to stop me adding more external drives until I have used up the USB sockets on the NUC.
This will be handy when I install an 8TB SSD internally. It would allow me to add an external 1TB HDD temporarily to preserve the files on my 1TB internal SSD while it replace it with the new 8TB SSD. Finally. I’d copy all the files From both drives on to the new SSD and disconnect the external drives.
I have a Roon Nucleus connected by ethernet and HDMI. I have a 1TB USB HDD connected for nightly backups. If I had lots of music, I would install the largest SSD that would fit inside. If I needed more, I would plug the largest SSD into the second USB port. Problem solved.
If you only have one USB port, I would think you could use a USB hub for music drive and backup drive, but IDK.
It is recommended if you are doing wholesale moves of content from one drive to another that you disable the location they are in, stop roon server while moving the data then add the new location IIRC… check in the KB’s
Thanks, I didn’t know that. What’s KB?
and specifically step 3
Knowledge Base, also KeyBoard, and KiloByte. We love our acronyms.
seriously??? 
Oh yeah, one of the acronyms in desktop servicing is PBCK, problem between chair and keyboard. 
I had a teacher in high school that used to say the fault was “a loose nut behind the keyboard”