Users Guide

Dynamic Power Supply Engagement
Dynamic Power Supply Engagement (DPSE) mode is disabled by default. DPSE saves power by optimizing the power efficiency of
the PSUs supplying power to the chassis. This also increases the PSU life, and reduces heat generation.
CMC monitors total enclosure power allocation, and moves the PSUs to Standby state. Moving the PSUs to standby state:
• Enables delivery of the total power allocation of the chassis through fewer PSUs.
• Increases the efficiency of the online PSUs as they run at higher utilization.
• Improves the efficiency and durability of the standby PSUs.
To operate remaining PSUs at their maximum efficiency:
• No Redundancy mode with DPSE is highly power efficient, with optimal PSUs online. PSUs that are not needed are placed in
standby mode.
• PSU Redundancy mode with DPSE also provides power efficiency. At least two supplies are online. One PSU powers the
configuration, while the other provides redundancy in case of PSU failure. PSU Redundancy mode offers protection against the
failure of any one PSU, but offers no protection in the event of an AC grid loss.
• Grid Redundancy mode with DPSE, where at least two of the supplies are active, one on each power grid, provides a good
balance between efficiency and maximum availability for a partially loaded modular enclosure configuration.
• Disabling DPSE provides the lowest efficiency as all six supplies are active and share the load. This results in lower utilization of
each power supply.
DPSE can be enabled for all three power supply redundancy configurations — No Redundancy, Power Supply Redundancy, and
Grid Redundancy.
• In a No Redundancy configuration with DPSE, the M1000e can have up to five power supply units in Standby state. In a six
PSU configuration, some PSU units are placed in Standby and stay unutilized to improve power efficiency. Removal or failure of
an online PSU in this configuration causes a PSU in Standby state to become Online. However, standby PSUs can take up to 2
seconds to become active, so some server modules may lose power during the transition in the No Redundancy configuration.
NOTE: In a three PSU configuration, server load may prevent any PSUs from transitioning to Standby
• In a Power Supply Redundancy configuration, the enclosure always keeps an additional PSU powered on and marked Online in
addition to the PSUs required to turn on the enclosure. Power utilization is monitored and up to four PSUs could be moved to
Standby state depending on the overall system load. In a six PSU configuration, a minimum of two power supply units are always
turned on.
Since an enclosure in the Power Supply Redundancy configuration always has an extra PSU engaged, the enclosure can
withstand the loss of one online PSU. The enclosure can also have enough power for the installed server modules. The loss of
the online PSU causes a standby PSU to come online. Simultaneous failure of multiple PSUs may result in the loss of power to
some server modules while the standby PSUs are turning on.
• In Grid Redundancy configuration, all power supplies are engaged when the chassis is turned on. Power utilization is monitored,
and if system configuration and power utilization allows, PSUs are moved to the Standby state. The Online status of PSUs in a
grid mirrors that of the other grid. Hence, the enclosure can sustain the loss of power to an entire grid without interruption of
power to the enclosure.
An increase in power demand in the Grid Redundancy configuration causes the engagement of PSUs from the Standby state.
This maintains the mirrored configuration needed for dual-grid redundancy.
NOTE: With DPSE Enabled, the Standby PSUs are brought Online to reclaim power if power demand increases in all
three Power Redundancy policy modes.
Default Redundancy Configuration
The default redundancy configuration for a chassis depends on the number of PSUs it contains, as shown in the following table.
Table 38. Default Redundancy Configuration
PSU Configuration Default Redundancy Policy Default Dynamic PSU Engagement Setting
Six PSUs Grid Redundancy Disabled
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