1. A datacenter, comprising:a hot aisle and a cold aisle defining a plane separating a hot side and a cold side, with the hot side being positioned on one side of the plane and the cold side being positioned on an opposite side of the plane;
a first rail and a second rail mounted at the plane, each of the first and second rails being oriented in a first direction and at least one of the first and second rails being movable in a second direction orthogonal to the first direction;
one or more filler plates mounted between the first and second rails and between the hot side and the cold side; and
a rack having one or more electronic components and one or more openings adjacent the one or more electronic components to engage the first and second rails, such that the one or more openings in the rack are blocked by the one or more filler plates.