Redundancy Policies

Redundancy policy is a configurable set of properties that determine how CMC manages power to the chassis. The following redundancy policies are configurable with or without dynamic PSU engagement:

Grid redundancy

Power supply redundancy

Grid Redundancy Policy

The purpose of the Grid redundancy policy is to enable a modular enclosure system to operate in a mode in which it can tolerate AC power failures. These failures may originate in the AC power grid, the cabling and delivery, or a PSU itself.

When you configure a system for Grid redundancy, the PSUs are divided into grids: PSUs in slots 1 and 2 are in the first grid while PSUs in slots 3 and 4 are in the second grid. CMC manages power so that if there is a failure of either grid, the system continues to operate without any degradation. Grid redundancy also tolerates failures of individual PSUs.

NOTE: One role of Grid redundancy is to provide seamless server operation despite failure of a whole power grid, but the most power is available to maintain Grid redundancy when the capacities of the two grids are approximately equal.

NOTE: Grid redundancy is only met when the load requirements do not exceed the capacity of the weakest power grid.

Grid Redundancy Levels

One PSU in each grid is the minimum configuration necessary for use as grid redundant. Additional configurations are possible with every combination that has at least one PSU in each grid. However, to make the maximum power available for use, the total power of the PSUs in each leg should be as close to equal as practical. The upper limit of power while maintaining Grid redundancy is the power available on the weakest of the two grids.

If a CMC is unable to maintain Grid redundancy, an e-mail and/or SNMP alert is sent to administrators, if the Redundancy Lost event is configured for alerting.

In the event of a single PSU not functioning in this configuration, the remaining PSUs in the problematic grid are marked as online. In this state, the PSUs in the Redundant Grid if not in failed state, help in functioning of the system without interruption. If a PSU stops functioning, the chassis health is marked non-critical. If the smaller grid cannot support the total chassis power allocations, then Grid redundancy status is reported as No, and the health of chassis is displayed as Critical.

Power Supply Redundancy Policy

The power supply redundancy policy is useful when redundant power grids are not available, but you may want to be protected against a single PSU failure bringing down your servers in a modular enclosure. The highest capacity PSU is kept in online reserve for this purpose. This forms a Power Supply redundancy pool.

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Dell 2 manual Redundancy Policies, Grid Redundancy Policy, Power Supply Redundancy Policy, Grid Redundancy Levels