If you are doing UConUCS Tested Reference Configuration, or a BE6000 / BE7000 appliance, then we prescribe the RAID.
High-level summary in this table: http://docwiki.cisco.com/wiki/UC_Virtualization_Supported_Hardware#Table_1_-_UC_on_UCS_TRCs
More details here: http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/virtual/CUCM_BK_CF3D71B4_00_cucm_virtual_servers.html
If you are doing specs-based-UCS, you have more flexibility on storage setup but the Collab BU can’t provide as much help validating your BOM or configuration.
-james