I have a 2011 15" MBP. Currently, I have a dual drive setup with a 750GB Scorpio Black in the Optibay. Everthing's been great so far except this click/scratch sound that occasionally comes from the Scorpio Black. I tried a small freefall test to make sure it wasn't the SMS. It's alot louder and longer than the SMS click. Weirdly, it sounds exactly like the lock sound on my iPhone. So far I've tried: - Repairing the drive - worked for a couple days, but sound eventually came back - Downloaded SMART Utility demo. Load cycle count seems normal (17490 at ~3 months of use). Testing didn't turn up any bad sectors, but I don't know the limitations of the demo. I know it's probably the drive heads parking, but I want to know if anyone has a definitive answer as to whether I should return it. If it's is harmless, then I'd rather live with it than go through the hassle of returning it. I die a little inside every time I hear that scratching sound, but I'm just way too lazy busy to go digging in there again.