Users Guide

When a server is turned on in an enclosure, the iDRAC software reestimates the power requirements and requests a subsequent change in
the power envelope.
CMC supplies the requested power to the server, and the allocated wattage is subtracted from the available budget. After the server is
granted a power request, the server's iDRAC software continuously monitors the actual power consumption. On the basis of actual power
requirements, the iDRAC power envelope may change over a period of time. iDRAC requests a power step up if the servers are fully using
the allocated power.
Under heavy load, the performance of the processors on the server may be degraded to ensure power consumption stays lower than the
user-congured System Input Power Cap.
The PowerEdge VRTX enclosure can supply enough power for peak performance of most server congurations, but many available server
congurations do not consume the maximum power that the enclosure can supply. To help datacenters allocate power for their enclosures,
the PowerEdge VRTX allows you to specify a System Input Power Cap to make sure that the overall chassis AC power draw stays within a
given threshold point. CMC rst makes sure that enough power is available to run the fans, I/O module, storage adapters, physical disk
drive, main board, and CMC itself. This power allocation is called the Input Power Allocated to Chassis Infrastructure. After Chassis
infrastructure, the servers in an enclosure are turned on. Any attempt to set a System Input Power Cap less than the “Power Burden” will
not be successful. Power Burden is the sum of power allocated to the infrastructure and the minimum power allocated for the powered
servers.
NOTE: To use the Power Cap feature, you must have an Enterprise License.
If necessary for the total power budget to stay below the value of the System Input Power Cap, CMC allocates servers a value less than
their maximum requested power. Servers are allocated power based on their Server Priority setting, with higher priority servers getting
maximum power, priority 2 servers getting power after priority 1 servers, and so on. Lower priority servers may get less power than priority-
one servers based on System Input Max Power Capacity, and the user-congured setting of System Input Power Cap.
Conguration changes, such as an additional server, shared HDDs, or PCIe cards in the chassis, may require the System Input Power Cap
to be increased. Power needs in a modular enclosure also increase when thermal conditions change and the fans are required to run at
higher speed, which causes them to consume additional power. Insertion of I/O module and storage adapters, PCIe cards, physical disk,
main board; number, type, and conguration of PSUs also increase the power needs of the modular enclosure. A fairly small amount of
power is consumed by servers even when they are powered down to keep the management controller powered up.
Additional servers can be powered up in the modular enclosure only if sucient power is available. The System Input Power Cap can be
increased any time up to a maximum value of 5000 Watt to allow the power up of additional servers.
Changes in the modular enclosure that reduce the power allocation are:
• Server turned o
• I/O module turned o
• Storage adapters, PCIe cards, physical disk drive, and main board turned o
• Transition of the chassis to a turned-o state
You can recongure the System Input Power Cap when the chassis is either turned on or turned o.
Server Slot Power Priority Settings
CMC allows you to set a power priority for each of the four server slots in an enclosure. The priority settings are 1 (highest) through 9
(lowest). These settings are assigned to slots in the chassis, and the priority of the slots is inherited by any server inserted in that slot.
CMC uses slot priority to preferentially budget power to the highest priority servers in the enclosure.
According to the default server slot priority setting, power is equally apportioned to all slots. Changing the slot priorities allows
administrators to prioritize the servers that are given preference for power allocations. If the more critical server modules are left at their
default slot priority of 1, and the less critical server modules are changed to lower priority value of 2 or higher, the priority 1 server modules
is powered on rst. These higher priority servers get their maximum power allocation, while lower priority servers may be not be allocated
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Managing and Monitoring Power