external disk still spinning after ejecting during encryption I was recently fiddling with my external drive and retroactively encrypting the partitions. I have two on there, one from my previous 2010 macbook, and my current 2015 macbook. For the 2015 one, I followed CCC directions and encrypted by using it as my startup disk and turning on FileVault2. For the 2010 version, since I am not using it as a bootable clone (I couldn't even if I wanted to because of hardware incompatibilities... unless I really had a strong urge to), I read that I could just encrypt it by right-clicking it from my desktop and selecting "Encrypt". 

The problem is, I was spaced out and ejected the entire disk while encrypting the 2010 partition (2015 was completely finished). I have no way to tell if it was still encrypting but it was a couple minutes after it told me to restart to continue with the initial (2010 partition) encryption. Even though I didn't encrypt the FileVault2-way (again, for the 2010 partition), I presume it still takes a considerable amount of time. But, there's not indication of when it's done! Now, when I eject it, the disk won't stop spinning.

The good news is, I never physically unplugged the disk from it's USB connection. So perhaps it's still doing it's thing behind the scenes? Please help.
Check the offending process using Console.app. Inside of your logs, search for something like “mount”...