Everest Random Access Time
Everest Ultimate and Corporate Edition offer several different benchmarks for testing and optimizing your system or network. The Random Access test is one of very few if not only that will measure hard drives random access times in hundredths of milliseconds as oppose to tens of milliseconds.
The read access times with the Caviar Black are lower than the Barracuda XT by a good margin. This amount of latency reduction would definitely be noticeable if you were using either of these drives as an operating system drive that you boot off of.
Western Digital has really done a good job with their cache and the chart shows just how much lower the write latency is compared to the Barracuda XT.
Let's see how all of these synthetic benchmarks relate to real world applications.