We apologize for the inconvenience, but this procedure would not work to extend your RAID size.
If you remove 2 hard drives from the RAID 10 and rebuild to new disks, the size of the volume will not change, regardless of the disk sizes. In this case, the 2TB disks will only use 320GB of space for the RAID, and the remaining space not be used at all. Option 10, "Tell ICH to expand the array to fill the 2TB drive set", is not really an option in this case.
If you are going to purchase new disks, I recommend creating a new array and transferring the data directly. \
As an alternative, you can connect one of the 2TB disks and leave all the disks on your RAID 10 connected to the system. After you transfer all the files, migrate that 2TB to a new array, using the Intel(R) Rapid Storage Technology.
For more information, please refer to the following website: