Abstract: A modular housing for first and second groups of replaceable functional units, e.g., disk files comprises a chassis for supporting the units within a first compartment extending along the length of a chassis support structure and removable via opposite openings in the chassis. Replaceable cooling and power supply assemblies are located within a second compartment of the drawer and can be removed from drawer via one of the openings without removing either of the groups of functional units. The fan of a combined cooling and power supply unit is arranged centrally within the second compartment such that it draws cooling air past the first group of units and exhausts air towards the second group of units.