Question: what is a 2u rack?
Answer: You may find "1U" or" 2U" when you look at the product information of the rackmount server. ... A 19-inch rack means that the width of which is 19 inches. The height of this rack is expressed in "units" called U (unit). 1U is 1.75 inches. So, 2U is 3.5 inches high and 4U is 7 inches high.