You haven't really described your configuration - maybe by the time we're done we can enhance Jorton's list to include device-specific settings to ensure a trouble-free setup.
Do you mind outlining all of your switch settings, for both the internal and external swtiches? As I mentioned in an earlier post, there's a Mediasonic forum post from Mediasonic staff that describes how to set the switches relating to volumes either larger or smaller than 2TB. The Revision C of the User Instructions does not explain this at all.
The rule, according to the post, is to take into account the final, available space - which of course would differ depending on which RAID type you employ - for example - RAID 0 on 2 X 2TB drives would yield something just short of 4TB total space, so that would dictate you would set your DIP switches to be RAID 0, with more than 2 TB of total available space. On a RAID 1 array with 2 X 2TB drives, your yield would be a little less than 2 TB, which would dictate that you set your switches to RAID 1, with less than 2 TB of total available space. Worth double-checking.
I also agree with Reboot's recommendation to turn the Synchronization switch off.
As amosnov suggested, it is a useful activity to install the drives, create the RAID array and initialize it with MBR using a Windows computer. If it passes the muster, the result will show in the Disk Management utility as one contiguous unallocated space which should equal the expected size of your RAID volume (which, in the case of a RAID 1 configuration on 2 x 2TB drives is 1,8900-odd GB because of overhead).
After this prep is done, the introduction of the Mediasonic box on the Gateway should be straightforward - it does not have to create the array (that's already complete), it just has to format the unallocated space and mark it as an available, writable volume. In my case, it took barely 5 minutes to prepare once the Gateway recognized it.
I would not expect to have to reset the RAID array once you have confirmed it is a working RAID set through the Windows Disk Management activities already discussed. To me, this would only be necessary if the Gateway was actually introducing an undesirable effect on the RAID array - in which case, we should all be concerned.
Hope this helps - looking forward to hearing how you've set your switches.