Dell Chassis Management Controller Version 1.3 for PowerEdge FX2/FX2s User's Guide

The Grid Redundancy policy is also knows as 1+1 policy, for one active and one spare PSU.

The purpose of the Grid Redundancy policy is to enable an enclosure system to operate in a mode in which the enclosure can tolerate AC power failures. These failures may originate in the AC power grid, the cabling and delivery, or a Power Supply Unit (PSU) itself. When you configure a system for Grid Redundancy, connect PSUs 1 and 2 to separate power grids.

In this mode, the CMC ensures that power usage is maintained such that the system continues to operate with no degradation if there is a failure of either the grid or a single PSU. Server power-on is limited to the available power of a single PSU. If at any time redundancy cannot be maintained (such as if a PSU is removed or fails) alerts are triggered, the chassis health becomes Critical.