A retention assembly includes a first retention member with a first set of ribs and a second set of ribs. The first set of ribs are positioned to form slots, which are shaped to receive data storage devices. The first set of ribs are arranged to separate adjacent data storage devices and have a first length. The second set of ribs extend into respective slots to form air channels within the slots, and the second set of ribs have a second length that is shorter than the first length.