If you’ve got a large iTunes library–and even if yours isn’t of epic scale–you’ve probably spent a lot of time buying music, ripping CDs, tagging files, and organizing playlists. It’s essential that you back up all this content. If your hard disk goes belly up, you’ll lose a lot of music and videos, as well as other content.
You can re-download some purchased content from the iTunes Store (but not all; see below). You may be able to re-download content purchased from other online music vendors, such as Amazon, or if you purchase directly from label sites. But if you’ve ripped a thousand CDs, remember how long it took for each one of them? This takes even longer if you rip DVDs or Blu-Rays. If need to rip them again, that would take weeks.
So, to make sure you never lose any of this content, you need to back up your iTunes library and other media files regularly. Here’s how to do it.
Read the rest of the article on the Mac Security Blog.