Users Guide

power requirements, the iDRAC power envelope may change over time. iDRAC requests a power step-up only if the servers are fully
consuming the allocated power.
Under heavy load the performance of the server’s processors may be degraded to ensure power consumption stays lower than the user-
congured System Input Power Cap.
The PowerEdge M1000e 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 data centers provision power for their
enclosures, the M1000e allows you to specify a System Input Power Cap to ensure that the overall chassis AC power draw stays under a
given threshold. CMC rst ensures enough power is available to run the fans, IO Modules, iKVM (if present), and CMC itself. This power
allocation is called the Input Power Allocated to Chassis Infrastructure. Following Chassis Infrastructure, the servers in an enclosure are
powered up. Any attempt to set a System Input Power Cap less than the actual consumption fails.
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
1 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 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 modules and iKVM also increases 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 16685 watts to allow the power up of additional servers.
Changes in the modular enclosure that reduce the power allocation are:
• Server power o
• Server
• I/O module
• iKVM removal
• Transition of the chassis to a powered o state
You can recongure the System Input Power Cap when chassis is either ON or OFF.
Server Slot Power Priority Settings
CMC allows you to set a power priority for each of the sixteen 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 slot's priority 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
enough power to run at their maximum performance or they may not even power on at all, depending on how low the system input power
cap is set and the server power requirements.
If an administrator manually powers on the low priority server modules before the higher priority ones, then the low priority server modules
are the rst modules to have their power allocation lowered down to the minimum value, in order to accommodate the higher priority
servers. Therefore, after the available power for allocation is exhausted, then CMC reclaims power from lower or equal priority servers until
they are at their minimum power level.
NOTE
: I/O modules, fans, and iKVM (if present) are given the highest priority. CMC reclaims power only from lower priority
devices to meet the power needs of a higher priority module or server.
Managing and Monitoring Power 225