I have three of the 2TB WD Passport USB drives. The first one I bought spins smooth a silk. If you lay your hand on it you can feel when the read head moves, but can't feel the drive spinning. With the second one I bought, you can clearly feel the drive spinning, as there is a definite vibration. The third drive falls in the middle with a constant, but light, vibration.
The question is what is normal for these drives? Should I be concerned about early drive failures based on these results?