User's Manual

Power Management 253
Figure 8-6. Chassis With Six-PSU Configuration
The CMC maintains a power budget for the enclosure that reserves the
necessary wattage for all installed servers and components.
The CMC allocates power to the CMC infrastructure and the blade servers in
the chassis. The CMC infrastructure consists of components in the chassis,
such as fans, I/O modules, and iKVM (if present). The chassis may have up to
16 blade servers that communicate to the chassis through the iDRAC. For more
information, see the iDRAC User’s Guide at support.dell.com/manuals.
The iDRAC provides the CMC with its power envelope requirements before
powering up the blade server. The power envelope consists of the maximum
and minimum power requirements that could keep the server operating.
iDRAC’s initial estimate is based on a worst-case model where all
components in the blade server draw maximum power and are often higher
than the actual blade requirements.
When a server is powered-up in an enclosure, the iDRAC software re-estimates
the power requirements and requests a subsequent change in the power
envelope (usually a reduced power envelope).
PSU1 PSU2 PSU3 PSU4 PSU5 PSU6