The Benchmark Results - Transfer Rate of ATA Stripe Sets, Continued
Here you can see the same in numbers. If you look at the 'ending transfer rate', you will see that the bandwidth is directly proportional to the number of drives in the array. The 'beginning transfer rate' however shows that the stripe of three and four is cut off.
This graph should show how much of the possible bandwidth is indeed cut off by FastTrak66. The stripe of two hard drives delivers exactly as we expect it. The stripe of three loses some 8 MB/s in the first three zones of the hard drives. Striping four fast drives creates a loss of some hefty 20+ MB/s in bandwidth over the first 7 zones though. Only the last 4 zones are represented properly.
This strange behavior is most likely caused by bandwidth problems within FastTrak66. The controller is simply not able to transfer data that fast. The other possible explanation could be the PCI-bus. 133 MB/s are an ideal mark that can only be reached if no other device is using the PCI bus. However, this does not explain the loss in case of the stripe of three, since FastTrak66 is obviously able to transfer more than 61 MB/s once you are using four drives.