This got a bit long winded but...
I agree with Dennis that RAID 1 does not give great data protection. The problem with a simple RAID 1 mirror is that when one drive dies, its likely the same age as the other and chances are the surviving drive isnt far behind. When you pop in the replacement for the first casualty, you could lose the other drive in the set while the array rebuilds, leaving you with whatever you may have been lucky enough to copy to the new drive. However RAID 5 still can only tolerate a single drive failure. My mission critical stuff at work goes on a RAID 6 array which will tolerate a failure of any two disks, but its not a feasible solution for a home user. I think we paid about $17k for our 12 disk array several years ago.
For a home user that can tolerate some down time during a restore the best protection is a decent backup strategy. With music, you probably are not adding much content on a regular basis. Whenever you add new content, run a fresh backup to an inexpensive external drive. If you really want to be extra safe, buy two inexpensive external drives and run the backup twice, once to each drive. You say iTunes, not sure that means you are using a Mac computer, but if so here is a link on how this works with Time Machine:
https://www.lifewire.com/time-machine-multiple-drives-how-to-use-2260099
Another option, since you are on iTunes, is to use the cloud. Not sure if you have heard about the iTunes Match service, but for $25 a year Apple will maintain your entire music collection, up to 100,000 songs, in their cloud. Any content you may have purchased from iTunes does not count towards that limit. This also gives you streaming access to your content from anywhere.
https://support.apple.com/en-us/HT204146
If you have a Verizon unlimited data plan other than their most basic plan, it includes
Apple Music for free, which is like iTunes Match but also includes Apples library of 50 million songs. We just switched to the Verizon unlimited plan. I am using Apple Music and really enjoy it.
And speaking of Verizon, I assume everyone has heard about the free year of Disney+ you get with any of the Verizon Unlimited plans:
https://www.verizonwireless.com/solutions-and-services/disneyplus/