Figure 2 in the accompanying power point file shows historical storage areal density (AD) growth for HDDs (this is directly related to the amount of digital storage that can be put on a disk in a hard disk drive) from Q1 2000 through Q1 2011.

FORBES: Why Government Regulators Should Approve Hard Disk Drive Company Consolidation

Providing this storage capacity with HDDs and with slower areal density growth than in the past will require more HDD components and a major investment in HDD component capital equipment.

FORBES: Digital Storage Needs the Right Stuff