IBM NeXtScale System, Planning And Implementation Manual

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Chapter 7. Hardware management
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򐂰 N+1: One of the power supplies is redundant, so a single faulty power supply
is allowed.
򐂰
N+N: Half of the PSUs that are installed are redundant, so the enclosure can
support up to N faulty power supply units.
Figure 7-19 Power supply redundancy mode configuration
Oversubscription option (OVS) is only selectable when N+1 or N+N redundancy
modes are enabled. When oversubscription is enabled, the enclosure uses the
extra power from the redundant power supplies. Oversubscription allows
compute nodes to demand more power than is allowed by the redundancy power
that were selected.
The power budget that is available to grant power permission to systems that are
installed in the chassis depends directly on the capacity of the power supply units
that are installed, the demanding power of the nodes, the redundancy mode that
was selected, and oversubscription enablement.
For more information, see 3.8, “Power management” on page 52.
Power Cap tab
The Power Cap tab allows setting power capping and power saving modes at
chassis or node level. Both power capping and power saving modes can be
applied simultaneously.
Power capping at chassis level is selected at the drop-down menu. A range is
suggested that is based on the minimum and maximum power consumption of
the systems that are installed in the chassis. Any value that is not set within the
suggested range is allowed; but if it is below the minimum, it might not be
reached.