The Register interprets a recent analyst briefing by Seagate as predicting that this year could see the long-awaited 4TB 3.5" drive introduction. This is based on Seagate's claim of a 6-th generation of Perpendicular Magnetic Recording (PMR) technology, and The Register's guess that this would provide a 30% increase in areal density. Thomas Coughlin makes similar projections but with only an 18% increase in areal density. These projections can be viewed optimistically, as continuing the somewhat slower growth in capacity of recent years, or pessimistically, as the industry being forced to stretch PMR technology because the transition to newer technologies (HARM and BPM) offering much higher densities is proving much more difficult and expensive than anticipated.
On a related note, Storage Newsletter reports on Trend Focus's estimate that the industry shipped 88 Exabytes of disk capacity in the last quarter of 2010, made up of 29.3 Exabytes of mobile drives, 48.4 Exabytes of desktop drives, 2.6 Exabytes of enterprise drives, and 8 Exabytes of drives for consumer equipment (primarily DVRs). There were 73 million mobile and 64 million desktop drives, confirming that the market is moving strongly to the (lower capacity) 2.5" form factor.
Cisco estimates that the global IP traffic was 15 Exabytes/month at the start of 2010 growing at 45%/year. If they were right, the rate at the end of 2010 would be 66 Exabytes per quarter. The 88 Exabytes per quarter rate of disk shipments is still capable of storing all the IP traffic in the world. Because unit shipments of disks are growing slowly, and the capacity of each unit is growing less than 45%/year, they will shortly become unable to do so.