Blog post details microbenchmark techniques to reverse-engineer physical HDD geometry (RPM, track layout, platter count, skew) across 17 drives from 45 MB to 5 TB.
Key Takeaways
Older geometry-detection algorithms like Skippy break on modern drives due to changed track-to-head ordering assumptions.
RPM, angular sector position, seek times, and track boundaries are all derivable from carefully timed sequential sector reads.
Full-stroke seeks take 1.3 to 3.6 revolutions; even short seeks are costly, limiting short-stroking gains.
Modern drives vary track size per recording surface, making zone definitions surface-specific rather than cylinder-wide.
On the newest tested drive, average track pitch is 80 nm and average bit length is 17 nm.
