HD Tune is a popular storage benchmarking utility that measures read and write speeds as well as random access performance.
Read and write performance of the new WD Black 4TB drive was generally impressive as it was markedly quicker than both its 1TB sibling and the old 300GB VelociRaptor drive - by around 20%. Nevertheless, it was outclassed by the latest 1TB VelociRaptor drive.
Looking at random access performance, the Caviar Black 4TB was just about on a par with the 1TB variant. The 300GB VelociRaptor drive, which was earlier outclassed by the Caviar Black 4TB, managed to claw back a win and posted appreciably higher average speeds and lower access times.