Hi Kazuki,
DMO is new feture of SUM Tool, that help us to do a system upgrade and DB migration in the same time for example.
Currently Is it a BW system + SQL Database ?
For BW sizing you need to consider note 1736976 and see http://service.sap.com/~sapidb/011000358700000221652013E
and please look this :
Licensing, Sizing and Architecting BW on HANA
Regards,
Edinaldo Junior