Music Servers/External Drives

I recommend using Exact Audio Copy for ripping CDs.  It provides a bit perfect rip and is free shareware.  I don't think that you can rip to ALAC, but conversion between ALAC, FLAC, WAV and many other lossy and lossless formats is easy with DBPowerAmp, which is my favorite conversion software.

I use a Seagate 5 terrabyte hard drive attached to Cambridge Audio N851 Azur for most of my listening and it sounds great.  It provides the flexibility to play all sorts of formats and high resolution files.  I do highly recommend using a good USB connection between the HD and your server/streamer.  I was skeptical, but adding an Audioquest Diamond USB 3.0 cable and an Audioquest Jitterbug between the Seagate and the 851N made the most dramatic difference in sound than any other cable improvement I have made.  The sound immediately became fuller, more present and nuanced in my system.  Good luck!   

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).