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-
configured System Input Power Cap.
The PowerEdge M1000e enclosure can supply enough power for peak performance of most server configurations, but many available
server configurations 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 first 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-configured setting of System Input Power Cap.
Configuration 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 sufficient 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 off
• Server
• I/O module
• iKVM removal
• Transition of the chassis to a powered off state
You can reconfigure 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 first. 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 first 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.
Assigning Priority Levels to Servers
Server priority levels determine which servers the CMC draws power from when additional power is required.
NOTE:
The priority you assign to a server is linked to the slot and not to the server itself. If you move the server to a
new slot, you must re-configure the priority for the new slot location.
NOTE: To perform power management actions, you must have Chassis Configuration Administrator privilege.
198 Managing and Monitoring Power