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July 18th, 2023 19:00
Dell R420 - Not Redundant policy sums the PSUs?
Hi,
I bought a used Dell R420 with dual CPU and two 350W PSUs, and I am concerned with one thing: does the Power Configuration set to "Not Redundant" sums up the power headroom? Would I have a maximum capacity of 700W?
Because in the Power Monitoring, it says the Failure Threshold is 938 Watts and the Warning Threshold is set to 854 Watts.
I am new to servers and can't find the answer.
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DELL-Charles R
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July 19th, 2023 10:00
Hello BertiniB,
In theory that would be correct as defined here. You are aware of the risk if the system requires more power that it's able to supply if there is one failed PSU.
* Not Redundant - Every PSU contributes to the server's power. This can allow the server to reach its maximum possible power draw, but the lack of redundancy also means that if one PSU fails, the server can experience an outage.
I'll add more information from the iDRAC in line help :
Power Supply Options
NOTE: This section is displayed only for iDRAC on Rack and Tower systems.
By default, iDRAC calculates the maximum power consumption for the system and based on this information, it sets the redundancy policy. If you subsequently change the hardware configuration, the redundancy policy does not automatically update.
Hot spare is a power supply feature that configures redundant Power Supply Units (PSUs) to turn off depending on the server load. This allows the remaining PSUs to operate at a higher load and efficiency. This requires PSUs that support this feature, so that it quickly powers ON when needed.
In a two PSU system, you must set the primary PSU (that must be ON.) In a four PSU system, you must set the pair of PSUs (1+3 or 2+4) that must be ON.
Power Factor Correction (PFC) configures the PSUs to disable the PFC when the server is powered off. In Standby Mode of PSU operation, the PSU has the ability to disable PFC circuitry through a system command. The efficiency improvement is seen as watts saved. Power factor is the ratio of real power consumed to the apparent power. When the AC load is partly capacitive or inductive, the current waveform is out of phase with the voltage. This requires additional AC current to be generated that is not consumed by the load, creating wasted I2R (W) losses in the distribution network. Therefore, to maximize the amount of capability on a specific phase, the PFC must be as close to 1 as possible.
Enter the following power supply redundancy settings, and click Apply to apply the settings.
Redundancy Policy
Select the redundancy policy:
• Not Redundant— In this mode, failure of a single PSU can power off the system.
• Input Power Redundant— In this mode, the system is functional in the event of failure of a PSU input circuit, provided the PSUs are connected to different input circuits. This is also called AC redundancy.
• PSU Redundant— Only available on systems with four PSUs. This is also called DC redundancy. This is only valid in a 2+1 PSU configuration. In this mode, the system is functional in the event of failure of a single PSU.
Hot Spare
Select Enable to enable hot spare. If not, select Disable. Hot spare allows you to power off and power on specific power supplies as more or less power is required to operate the system.
Primary Power Supply Unit
Select the primary power supply unit. You can select this only if Hot Spare is enabled.
Power Factor Correction
Select Enable to enable power factor correction. If not, select Disable.
Dell-Martin S
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July 19th, 2023 07:00
Hi,
The "Not Redundant" power configuration setting in Dell R420 does not sum up the power headroom. In this configuration, the power supply units (PSUs) are not redundant, meaning if one PSU fails, the server will lose power. It does not increase the maximum power capacity.
The power capacity of the server is determined by the combined wattage of the two PSUs. In your case, each PSU has a capacity of 350W, so the total maximum power capacity for your server would be 700W. However, it's important to note that the actual power consumption of the server will vary based on the components installed and the server's workload.
The power monitoring information you mentioned, such as the failure threshold and warning threshold, provides thresholds for power consumption levels at which the system will generate alerts or take action. If the power consumption exceeds the warning threshold, it may indicate that the server is operating near its maximum capacity, and if it exceeds the failure threshold, it could potentially lead to a shutdown or other issues.
To ensure optimal power management and redundancy, it is generally recommended to configure the server with redundant power supplies. This allows the server to continue running even if one PSU fails, providing an added level of reliability. If high availability and redundancy are important for your needs, you may consider upgrading to redundant PSUs for your Dell R420.
More Information under: https://dell.to/3rDYzOs
BertiniB
2 Posts
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July 19th, 2023 07:00
Currently I do have redundant Power Supplies, but this is not my concern today, I'm okay if the server shuts down if one PSU fails. So in theory, I could put a load of 600W on the server, and it would handle it, because it has two 350W PSUs set to Not Redundant without Hot Swap in iDRAC, right?