One embodiment of the present invention provides a system that proactively monitors a disk drive to detect an impending disk drive failure. During operation, the system obtains a time-varying electrical signal which is generated by the spindle rotation during operation of the disk drive. Next, the system extracts one or more inferential parameters associated with the spindle rotation from the time-varying electrical signal using a phase-sensitive detection. The system then performs proactive fault detection on the inferential parameters to detect an impending failure of the disk drive.