An apparatus and system are disclosed for a pool drain cover, the cover having a perforated ramp around its perimeter to which are attached a plurality of straight, horizontally disposed tubes, circumscribing channels with substantially continuous cross-sectional areas, each tube enclosing a channel extending the length of the tube of at least six inches. Each standby system determines the lag time between the generation of a consistent version of data on the primary system and the time that the consistent version is applied on the standby system. The coolant distribution unit has a first heat exchanger, a first cooling loop and a second cooling loop.