M.Intel® Board S2600CP how to add HDD bypassing existing RAID1?

Question

Hard disks

Good afternoon!
Please clarify, there is an Intel® S2600CP server motherboard in which RAID1 is configured of two SSD drives on which Windows Server 2019 is in turn spinning. The system was assembled according to a new one and RAID1 was configured using google in embedded server raid technology ii, nothing complicated. Now a complete stupor in the search for a solution, how can I add another HDD (it is full of information) as a separate storage without RAIDs, that is, as a simple disk, and not lose this information. By simply adding it to a free slot, it becomes visible at boot, but it is not in the loaded operating system.
Tell me please.