Compaq ProLiant BL e-Class System Overview and Planning

Compaq ProLiant BL e-Class System Overview and Planning 20
PDU
A PDU has one or two AC power inlets and multiple power outlets (12) to simplify power cord
management.
PDU Failure
The PDU may have an internal failure or its input circuit breaker may be tripped due to
over-current. A PDU single source of failure can also loosely be described as a situation
when the PDUs have tripped due to over-current. This term also loosely describes when
the PDU’s power cord is removed or the AC source supplying power to the PDU fails.
PDU Redundancy
A PDU configuration that enables a server blade enclosure (or rack of enclosures) to
survive a PDU failure by re-distributing the load to other PDUs provides PDU
redundancy.
Figure 8. PDU redundancy, single source of failure = AC source
Figure 8 shows an enclosure that can survive a power supply failure, PDU failure, or unplugged
PDU power cord.
Note: The AC source is single source of failure.
PDU redundancy implies the remaining PDU(s) and AC sources have sufficient capacity to safely
handle the re-distributed load.