I didnt get what you are doing exactly... So lets brake it down:
Server A: Has one 10GB volume with RAID 1
Server B: Has one 10GB volume RAID 1
Server A & B are building RAID 1 with open-e built in software RAID????
And you are trying to replicate files from Server A to B? but when you turn one of the servers down, you are loosing your files?
Are using degradded mode? You HDD are the same size?
Since you are testing, I recommend you to use a RAID controller. Open-e will not give you the option to extend your volume size if you are using S/W RAID. Also, H/W RAID is more stable...
Answer the previouse questions.. and let me know if you need further help.