(Edit: Sorry, didn’t realize I was necroing such an old post. Not sure why the forums showed me this as a recent activity…)
Presumably if users are installing internal m.2s and setting them up as a volume cache, they should provide suitable performance for Roon (assuming the RoonServer file share is placed on the volume the SSD cache is configured for) without needing additional SSDs in the system, no?
Also, the Roon database ends up being pretty small absolute storage wise, even for really gargantuan libraries. Expanding RAM in the system (NAS or ROCK or whatever) will also give you the benefit of the OS’ file system block cache that will also likely make Roon perform well even on spinning disks (at least once it’s had a chance to start up and the OS block cache has loaded it into RAM – if you reboot frequently then this approach will be less beneficial). Of course, RAM is also price inflated these days (and some of the smaller NAS units don’t really let you add much additional RAM), but it should still be cheaper than buying a pair of m.2 SSDs…
FWIW, I’ve got my Roon Core on a dedicated CentOS 7 system with 32GB of RAM and I see the OS’ block cache consuming a good chunk of that and I have zero performance complaints with Roon despite the system having a pair of 1TB 7200rpm HDDs in a RAID1 mirror as the storage. (The CPU is an E3-1270v6.)