Simple test: Write a program that generates random data and writes to your target array. Write 50 GB of random data and time it. If it takes 30 minutes, you are limited by the array write speed. If it takes less, re-post in the networking section.
I remember doing these tests at home, for fun, years ago. I actually bought two fibre NICs and put one in my machine and one in my wife's, then annoyed her by bringing my machine downstairs and tying hers up in testing. Nowadays, I can move data at the same speed over my Cat5 LAN.