I finally made the jump and both bought a subscription (yeahh) and also installed Rock on a brand new NUC (i7 16GB). I bought a NUC with 480GB of internal drive in hope of being able to use it for both system and music library however I cannot find how to add it. (Internal SSD , one drive, let the installer do anything in automatic mode).
Although I don’t use ROCK I’m pretty sure that you cannot use the same drive for the OS and your music library. ROCK will overwrite the entire SSD.
IIRC, you’ll need to add a network drive (SAMBA) or an external USB drive for the music library.
For your NUC with ROCK, you’d use an M2 SSD for the OS/database and a SATA SSD (or external USB or NAS) for your music library. Perhaps you can just add one or the other to your NUC. A 64GB M2 SSD (for the OS) is large enough.
As Mike says, you need a separate internal 2.5" drive (can be either SSD or HDD) to hold your music files. The drive must not be thicker than 9.5mm in order to fit in the NUC enclosure (and of course the NUC enclosure must be an “H” model, which has space to hold the extra drive).
As others have pointed out, ROCK does not allow you to use the same drive for the OS and your music files. There are a couple ways you could address this:
Purchase a small SSD drive and install ROCK on it, then reformat the 480GB drive you already purchased via ROCK’s webmenu and use it for your music.
Don’t use ROCK. Install your own Linux distro on the 480GB drive you purchased, and manually install Roon Core on it (there are several threads on the forums here with some guidance to do this with various Linux distros if you need some assistance with this). Then you can also store your music on the drive. (I recommend making a separate logical volume for the music mount point, but this isn’t strictly required.)