rpsuStatus reports whether the redundant power supply unit identified by rpsuIndex is physically plugged into the chassis (1) or absent (0). Admins monitor this to detect a missing or failed redundant PSU before the loss of power redundancy leads to an outage if the primary supply also fails. For example, an alert firing when rpsuStatus for bay 2 changes from 1 to 0 would tell an operator that the secondary power supply has been removed or lost power.