Here's a quick story that gets off to a scary start but has both a happy ending and an important message that might save you some pain someday. I just lost a hard drive. Specifically, the Western Digital drive that held my entire iTunes music library abruptly died without warning. I don't do streaming, so my entire music collection of roughly 30,000 songs resided on this drive. I'd estimate that somewhere between 1,500 and 3,000 are obscure enough that I would not be able to replace them if they were lost. I should be freaking out, but I'm not.
You see, I learned my lesson last time. I had a relatively recent backup of the drive. Aside from some iTunes play count data I'm not worried about, I don't think I lost anything. And because of the manner in which I've been backing up the failed drive (i.e., cloning the entire drive), all I had to do was unplug the failed drive and plug in its backup. After pointing iTunes to the library files on the new drive, and I was up and running. It probably took less than two minutes.
I've already ordered a replacement drive so I can make sure I am not without a backup for long, and I think I'll probably pick up a couple more the next time there is a sale I can't resist. I've heard that most external hard drives don't last longer than about 6 years, and I have at least 2 others that are probably older than that.
The moral of the story? Back up that hard drive! Sooner or later, they all fail. I'm not sure what I'd be doing right now if I did not have a functioning backup, but it wouldn't be pretty.