Dell POWEREDGE M1000E - Manual (Page 206)

consumption. Depending on the actual 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
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