We create the 2GB partition on install, but in order to use the rest for data, you need to create 2 logical Units on the RAID yourself first.
1- 2GB for the OS
2- The balance left over for data.

As for the BBU info, just use the option of writeback even with out BBU.

This can help:
http://www.open-e.com/service-and-su...ts-and-videos/
--Installing Open-E DSS V6
the above video will show how to install to Controller, it is same for DS V7