1.   The capacity was achieved by increasing storage density on the glass platter and adding one thin-film read-write head.

2.   Increasing storage density also lets companies make disk drives that are lighter and consume less energy.

3.   Moreover, it is still uncertain whether the rate at which storage density is increasing will slip from the staggering pace of recent years.

4.   The thinner materials are slightly more sensitive, he said, but the tradeoff is reduced storage density.