I purchased a Dell PERC 6/i which I expected to be able to read with 1000 Mbps. There is not much to do now, but there are some things I wanted knowledge about for another time.

I have configured it with four 2 TByte drives and RAID 6.
It have 256 MByt ram and transfer rate of 300 Mbps.
The benchmark test showed:

Min read rate: 136.3 Mbps
Max read rate: 329,6 Mbps
Avg read rate: 242,2 Mbps

What could I had done to get at least 1000 Mbps?

Is it normal for internal and external RAID controllers to have a lower transfer rate eg. 300 Mbps? (I did not noticed at the time that it was not 3 Gbps)

How would a RAID 10 had performed compared to RAID 6 or 5?

Would it have been better to use software RAID (Linux) with the internal 3 Gbps SATA controller?

UPDATE:
The drives is SATA III 6 Gbps.
http://www.seagate.com/files/staticfiles/docs/pdf/datasheet/disc/desktop-hdd-data-sheet-ds1770-1-1212us.pdf (2TB)