A support for computer data back-up units is designed to receive at least two distinct sizes of back-up units. The support has a bottom and at least one stationary wall perpendicular to the bottom. The support also has an additional wall extending perpendicularly to the bottom of the support and parallel to the stationary wall. The additional wall is mounted to be movable relative to the bottom of the support between at least two receiving slots respectively associated with the distinct sizes of the back-up units.