Hello,
I have a 500gb WD MyPassportAir that I use witn my 2013 MacBook Air to store my iTunes media collection. I notice that when I am playing music in iTunes, the drive emits a loud clicking sound every so often. I would normally not think anything of it because the drive never disconnects or shows any signs that it is not functioning properly. However, the clicking sound is loud enough for me to notice it so I wanted to see if this might be normal for this drive or if it could be a sign of failure. The drive is only a couple of months old and it passes the S.M.A.R.T. and quick disk check tests in the WD Utilities app. I am running OS X Mavericks on the MacBook and the drive is connected directly to one of the USB 3.0 ports with the original cable, not through a hub.
Thanks,
GH