How do traditional data center cooling methods, such as CRAC and CRAH units, work?

Traditional data center cooling methods, like Computer Room Air Conditioning (CRAC) and Computer Room Air Handling (CRAH) units, rely on raising the air temperature in the cold aisle, where cold air is supplied, and lowering the air temperature in the hot aisle, where hot air is exhausted. CRAC units are self-contained systems that cool the air, while CRAH units are typically connected to a central chiller plant and use chilled water to cool the air. Both methods aim to maintain a consistent and optimal temperature range within the data center.