A support apparatus for supporting a hard disk drive in a computer system to enable hard disk replacement under hot-swap operations, the apparatus comprises a rail, a primary bracket coupled to the rail, and a cage to which a hard disk drive is mountable and coupled to the primary bracket. The rail is mountable to a base element such as a main board or the chassis of a computer system. The cage is movable relative to the rail from an operating position to a first cage position, and subsequently from the first cage position toward a second cage position to provide a clearance space in front of the cage, in order to allow the hard disk drive mounted in the cage to be drawn out from the cage for replacement under hot-swap operations.