Music Servers/External Drives

Thank you all for your replies and detailed explanations. This is very useful information. 
SW

SSD with max. data transfer rates over 800 mbps.  This will work much better than 7200 rpm HDD with only 160 mbps in terms of indexing on the first setup or later update.  No moving parts inside SSD makes it less volunerable and hence longer life expectency.  After all, losing data after a long time collection is excruciating.  In addition, SSD reads data without generating vibration and is supposed to give less electric noise that compromises SQ.

Lanx0003 makes a good point.  If you use an external hard drive, BACK IT UP REGULARLY!!!  They have a tendency to fail with little or no notice.  I keep a clone of my main drive connected to a difference stereo in the house.  I find that the Seagates are the most reliable, but don't risk a catastrophic loss of a curated collection for failing to spend an additional $150 or so on a second hard drive.

 In addition, SSD reads data without generating vibration and is supposed to give less electric noise that compromises SQ.

Yes, although  as I understand it, this isn't  an issue if you're only using an HDD for local library storage with Roon (and not as the location where Roon Core is installed).  In Roon's storage settings, you set a path to the device.  Then Roon continually monitors it for new files.  When it finds them, it integrates them into your Roon library. In that scenario, I don't believe Roon goes back to the HDD to read the data for real-time playback (again, assuming Roon Core is not installed to that HDD).

No matter what drive solution you pick, make sure you have adequate backups. You can get a NAS unit with multiple drives, but even with that you should have an external drive backup that is not connected to your computer or network, in case of a virus or ransomware attack. Another copy should be kept off-site or in the cloud.

I used JRiver to rip all my CDs to FLAC files. They are stored on my desktop PC, but also backed up to a single-drive Buffalo NAS drive. All my streamers (Bluesound) are pointed to the NAS drive. I also have a copy on an external HD (disconnected from anything) and a copy in a cloud backup service.