My MyPassport external USB drive (older version, from 2010) works very well. But I noticed that after I unmount it in OS X, the drive continues to spin, and it even continues to read or write because I can hear the head moving around inside. So it keeps clicking (as if it was actively reading or writing). This is not a fan or anything, I can easily tell by holding the drive that it is still spinning, and I can also hear the head moving around inside. It usually does this for a good 10 minutes after unmounting, then it usually stops spinning. What is it doing?
The same happens with the model that I have (WDBY8L0020BBK), so I guess it’s normal .