I have an N5200. Recently I got an email alert letting me know the raid6 array was degraded because a drive had failed. It turned out another had failed a while back and I'd done nothing about it so I decided to replace all the drives with larger 1TB capacity drives (up from 400GB) as I was getting a bit low on space too.
I believe the 5200 kept the constant beep/tone going because a failure of a 3rd drive would have meant data loss. My question is how do you mute the beep/tone without disabling beep notification in the configuration setup?
By the way, it took about 3 days to re-build the array when replacing all drives, a long time, but I guess it has a lot of work to do, and the hot-swap process was so simple - very impressed with that.