User's Manual

224 Power Management
• Power Supply Redundancy mode with DPSE is also power efficient. Two
supplies are active, with one PSU required to power the configuration and
one to provide redundancy in case of PSU failure.
PSU Redundancy mode
offers protection against the failure of any one PSU, but does not protect
the user in the event of an AC grid loss.
•
AC Redundancy mode with DPSE, four of six supplies are active, two 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, resulting in lower utilization of each power supply.
The CMC will monitor total enclosure power allocation, and move PSUs not
required into Standby state, causing the total power allocation of the chassis
to be delivered through fewer PSUs. Since the online PSUs are more efficient
when running at higher utilization, this improves their efficiency while also
improving longevity of the standby PSUs.
DPSE can be enabled for all three of the power supply redundancy
configurations explained above: No Redundancy, Power Supply Redundancy
and AC Redundancy:
•In a No Redundancy configuration with DPSE, the M1000e can have up
to four power supply units in
Standby state; at least two PSUs always stay
online regardless of the number of PSUs in the enclosure. In a six PSU
configuration, at least three supplies will always be placed in
Standby and
stay unutilized, regardless of the power load on the chassis. Removal or
failure of an online PSU in this configuration will cause 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
one extra PSU turned on and marked
Redundant in addition to the one to
three PSUs required to power the enclosure. Power capacity is monitored,
and if there is excess power capacity for 5 minutes, up to four PSUs could