While Hitachi predicts to deliver 4TB drives by 2011, Western Digital has unveiled a drive with a storage density of 520GB per square inch. That means 3TB 3.5-inch drives by 2010.

Let the race begin!

Hitachi is making the bold claim that they will provide 4TB desktop (3.5-inch) and 1TB laptop (2.5-inch) drives within the next 4 years. The new recording heads are more than 2x smaller than existing gear or about 2,000 times smaller than a human hair.