Removing A Power Supply Unit - Dell EMC PowerEdge R6400 Installation And Service Manual

E43s series; e43s001

Table of Contents

Policy philosophy

Similar to Grid Redundancy, Fault Tolerant Redundancy is a conservative redundancy policy that ensures that the PowerEdge FX2 Shared

Infrastructure Chassis and all installed components will remain operational with no risk of shutdown in the event of an AC Grid or Power

Supply failure even when all installed components are simultaneously running at their worst case power consumption. New for Fault

Tolerant Redundancy is a limit on peak performance that occurs when redundancy is lost. Fault Tolerant Redundancy is able to maintain the

same conservative standards of redundancy as traditional Grid Redundancy by limiting peak power after redundancy is lost to levels which

will fit within the surviving Power Supply.

Policy control

As with all FX2 Redundancy Policies, while the two Power Supplies remain healthy, load is shared evenly between them and the capacity of

both Power Supplies is made available for use. In the event of an AC Grid or Power Supply failure, Power Controls will rapidly engage to

restrict the power consumption of the chassis and ensure that consumption is restricted to what a single Power Supply can support. In

addition to controls used with all FX2 Redundancy Policies, Fault Tolerant Redundancy also implements additional performance limiting

functionality which restricts the peak power after redundancy loss.

For a fully loaded chassis running at maximum potential power this can result in some observed performance reduction as the chassis

Power Control limits are enforced. In practice, customer workloads are often not at the maximum potential power and so practical

performance reduction during an AC Grid or Power Supply failure is often minor or even completely unnoticeable.

Power-on behavior after fault

In the event of an AC Grid or Power Supply failure, new chassis components will be allowed to power on provided that the maximum

potential power of the newly installed chassis components does not exceed the capacity of a single Power Supply when evaluated by the

chassis Power Budget Checks. This means that, while customers will note a chassis "Critical" state due to the loss of redundancy, they will

observe no difference in which chassis components are allowed to power on (both before and after a redundancy fault). This is because in

both cases, the chassis Power Budget Checks use the capacity of only a single Power Supply. This is a key difference from the other

PowerEdge FX2 Shared Infrastructure Chassis Redundancy Policies.

Logging behavior

As with all FX2 Redundancy Policies, when a Power Supply Unit fails, a log message will be generated. For the Fault Tolerant Redundancy

policy, a log message will also be recorded to note a "Loss of Redundancy". This message indicates that the system is continuing to operate

in a Non-Redundant state, and action is necessary to either restore power to a failed AC Grid or replace a failed Power Supply Unit. Details

in log messages make it possible to distinguish between these two cases. Finally, in the event that power on of a chassis component is

denied due to a Power Budget Check, the denial will be logged both in CMC logs and iDRAC logs (in the case of compute sleds).