It is possible to configure a RAID-5 on the 7045B-3 server if you add the optional LPZCR2 Card. You will need to disable the HostRAID support on the onboard controller and set the jumper on the LPZCR2 card to operate in SAS mode.
To Disable HostRAID: Without the LPZCR2 card plugged in, enter the HostRAID utility bios. Goto, Serial Select --> Controller Config --> HostRAID Support --> Disable.