From the 23 July 2001 issue of the "Rapidly Changing Face of Computing":
In 1995, according to the June Gilder Technology Report , all the computers in all the world contained a total of 200 terabytes of storage. This month — just six years later, the advent of commodity ($300) 100-gigabyte drives means that just 2,000 PCs could contain the world's storage of 1995. (There are about ten exabytes of storage overall all at this point in time — "half-a-millionfold growth in less than a decade." IDC estimates that the data stored by companies is growing at 80% per year.)
Looking forward, considering IBM's projections for 0.4-terabyte "Pixie Dust" drives in 2003, it will then take a mere 500 PCs to match all the storage, in all the world, of just eight years before. And we can expect that trend to continue.