This is a part from an IBM server dated 2008 that I want to reuse in my new computer. It essentially converts from 1 SAS port to 4 SATA ports. I’ll use the raid card to connect to it via SAS, but I do not know what the power port is and what the connector on the top is either
That is not a plane if you look close. That is thieving. The board layout had no copper there, but this can make the plating process more difficult to get consistent across the board. Usually this is added by the fab house to help them manufacture the board.