Default Redundancy Configuration; Ac Redundancy; Power Supply Redundancy - Dell PS-M4110 User Manual

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 power the enclosure. Power utilization is monitored and up to
284 Managing and Monitoring Power 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 powered on.
Since an enclosure in the Power Supply Redundancy configuration always has an extra PSU engaged, the
enclosure can tolerate the loss of one online PSU and still 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 powering up.
• In AC Redundancy configuration, all power supplies are engaged at chassis power up. Power utilization is
monitored, and if system configuration and power utilization allows, PSUs are moved to the Standby state. Since
the Online status of PSUs in a grid mirrors that of the other grid, the enclosure can sustain the loss of power to
an entire grid with no interruption of power to the enclosure.
An increase in power demand in the AC Redundancy configuration cause 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 34. Default Redundancy Configuration
PSU Configuration
Six PSUs
Three PSUs

AC Redundancy

In AC Redundancy mode with six PSUs, all six PSUs are active. The three PSUs on the left must connect to one AC
power grid, while the three PSUs on the right connect to another AC power grid.
CAUTION: To avoid a system failure and for AC Redundancy to work effectively, there must be a balanced set of
PSU properly cabled to separate AC grids.
If one AC grid fails, the PSUs on the functioning AC grid take over without interruption to the servers or infrastructure.
CAUTION: In AC redundancy mode, you must have balanced sets of PSUs (at least one PSU in each grid). If this
condition is not met, AC redundancy may not be possible.

Power Supply Redundancy

When power supply redundancy is enabled, a PSU in the chassis is kept as a spare, ensuring that the failure of any one
PSU does not cause the servers or chassis to power-down. Power Supply Redundancy mode requires up to four PSUs.
Additional PSUs, if present, are utilized to improve power efficiency of the system if DPSE is enabled. Subsequent
failures after loss of redundancy may cause the servers in the chassis to power down.
Default Redundancy Policy
AC Redundancy
No Redundancy
Default Dynamic PSU Engagement Setting
Disabled
Disabled
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