I imported my private MP3 collection (basically ripped from the CDs I bought years back) on my Mac into iTunes some years back. On my "Music" directory, I basically see my folder private, where I put my MP3 files with 15 GB, and iTunes, also with 15 GB. I guess that is where iTunes stored all the data after import.
I use the Music app1.0.6.10 on macOS Catalina 10.15.6 now instead of iTunes.
I am about to replace that old Mac book with a new one. My plan is to copy that private folder onto the new machine, and import again but I worry it won't that like "double" all the existing entries.
I saw this very old question, but I am rather looking for a more basic explanation about "option space", and best practices.
How do I get the same MP3s into Apple Music these days?
Best Answer
By default, iTunes/Music copies audio files to /Music/iTunes. If you've got 15 GB of music in two locations, then you've probably got them duplicated already.
When you get a new Mac, you can use Migration Assistant to copy all your files and settings, and the process will be handled automatically for you.
If you don't want to use Migration Assistant, you can just copy the 'iTunes' folder inside /Music. The new app will update its Library database will all your data.