Readers asked for individual hard drive test results when we published Part 1 of this article. This is why you will find separate hard drive results in all the benchmark charts.
We have added the access time for a single Samsung Spinpoint HD321KJ, so you can compare its access time to the delays we found for RAID 5 and RAID 6 arrays with multiple drives. As already seen in Part 1 of this article, the access times for RAID setups with multiple drives increase considerably. The main reason for this performance decrease is the rotational latency of all RAID member hard drives as well as additional latencies due to the parity. It’s interesting that RAID 5 or RAID 6 arrays with six or more hard drives easily double the average access time of a single SATA hard drive.
Interface bandwidth typically isn’t much of an issue when benchmarking individual hard drives, because today’s Serial ATA interfaces are fast enough to support even the fastest data transfer rates that modern hard drives can deliver. In this case, the interface bandwidth equals the controller bandwidth, which thus shows how much data the Areca ARC-1220 RAID5/6 controller can process. Obviously, less than 500 MB/s are the limit here.