Input grid redundancy mode (grid redundancy)
In grid redundancy mode, half of the power supply's output is allocated to the reserve power pool. The other half of the output is allocated to the available power pool.
Input grid redundancy mode provides enough reserve power to cover the worst case of 50% of power supply failure. Such an event might occur when a power grid fails. The system logically allocates the left two columns of power supply bays to Grid A. The system sums the output power of operational power supplies. The system repeats the same process for the right two columns (Grid B). Then, the system uses whichever grid is supplying the minimum power output as the available power pool. To use maximum power, the sum of power supply outputs of Grid A and Grid B power supply bays must be equal.
For example, suppose that a system has four 3000 watts (W) power supplies in Grid A bays and three 3000 W power supplies in Grid B bays. In grid redundancy mode, 12000 watts are available from Grid A and 9000 W from Grid B. The minimum of the two grids is 9000 W. So 9000 watts are allocated to the available power pool and 9000 watts are reserved1. If either grid fails, enough power is reserved that the remaining power supplies can still meet the 9000 W commitment.