No, Apple Music Didn't Delete Your Library
First published on 8 May 2016, edited on 28 August 2019
A note from the author in 2019: This article was last updated over three years ago, I make no guarantees that it's still accurate.
I've noticed that there has been quite a few angry posts about 'Apple Music Deleted my iTunes!' go zooming up my Facebook newsfeed (28 August 2019 Update: which I no longer have). This post will hopefully clear up some of that confusion.
I'd first like to preface this by saying: No, Apple Music didn't delete your iTunes Library. You did.
Back in January when I purchased my first MacBook Pro, the salesman at the store suggested that I should take a look at Apple Music when I was finished setting up iTunes. I was particularly interested at the notion of being able to stream my 6,000-some song library to my phone without using an app like Subsonic. So, I took the iGenius's advice and activated the free, three month trial for Apple Music, figuring I had nothing to lose (on a related note, disabling the auto-billing when the three months ended was a bit of a pain, see here for how to do this).
Upon activating Apple Music, two things occur: 1) it started scanning my iTunes Library in an attempt to match my songs with the ones that Apple Music offers, and 2) the Apple Music tab appeared at the top of the iTunes window. Let's talk about 1) since this seems to be where most of the confusion comes from. To best know what's going on here, you'll need to show the 'iCloud Status' column in your music library. The terms that I use here come right from that column. When the service first starts scanning your library, the iCloud Status of every song will change to 'Waiting'. All this means is that individual song has yet to be dealt with.
So far so good, right? Once Apple Music is finished scanning a song, one of two things will happen: 1) if the song exists in Apple Music's library, the status will change to 'Apple Music', or 2) the song does not exist in Apple Music, so iTunes will upload the song to your iCloud Music Library. In this case, the status will say 'Uploaded'. Do keep in mind that on your computer, nothing has changed. Your music files, be they MP3's, AAC's, ALAC's or even WAV's, are still exactly where they were before (if you use the default settings, on a Mac this'll be in /Users/YOUR_NAME/Music/iTunes and on Windows it'll be in C:\Users\YOUR_NAME\Music\iTunes).
To reiterate: your files have not been changed at all. Read it again. Your. Files. Have. Not. Been. Changed. So where exactly does the misconception that Apple Music kills your library come from? Based on my experience in using the service, the problem is due to a single, poorly designed dialog box:
This is the popup that you get when you try to delete any song when you have Apple Music, and it's probably not the best example of good interface design. Clicking 'Delete Song' doesn't actually delete the song in question. Instead it removes the song from your iCloud Music library and sets its iCloud Status back to 'Waiting'. Clicking 'Remove Download' on the other hand deletes the music file from your computer and instead uses the version on the Apple Music servers. This is also the version that contains the DRM that causes the song to be unplayable when you cancel your subscription. The lesson here? Don't click 'Remove Download' on the computer that you keep your music files on. This option is intended for people who have multiple computers or phones connected to their Apple Music account. Note that this option is perfectly safe to click on secondary computers, just make sure to not click it on your primary computer.
So to conclude, no, Apple Music didn't brutally murder your iTunes Library. You did by clicking 'Remove Download' in an effort to save disk space. So please, stop crowding my Facebook newsfeed with posts that your library got deleted. First of all that problem can easily by avoided by reading the dialog box. Second, you should have a current backup of your library anyway. If you don't, go make one right now, you'll thank me later.