Think hard drives have hit their storage limits, and should be replaced by solid-state units? You could be wrong.  Hard drives have been holding our data for nearly 70 years since IBM created the 350, which stored something like 4 Mbyte on dozens of spinning disks in a unit the size of a washing machine. Today's devices are orders of magnitude better on every axis including price, capacity, size, and performance. But solid-state providers say it's time they moved over to make way for modern storage. Hard drives have been in a slump, but a new technique promises to double their capacity.  Seagate is the first to bring heat-assisted magnetic recording (HAMR) to the market, so we invited chief commercial officer B S Teh to tell us why it is such a big deal, why it's taken so long - and how it could change what you do in your data center.