HP BladeSystem p-Class rack-centralized (3U) power solutions

How workloads affect power requirements
Power requirements can be categorized into idle, maximum, and typical workloads.
Idle power requirements can be defined as the amount of wattage required to leave all servers
powered on, but not executing any applications. In general, when all server blades connected to the
power subsystem are idle, the HP BladeSystem power subsystem draws approximately 60 percent of
the maximum power level.
The maximum load for any configuration is calculated using the
HP BL p-Class Sizing Utility.
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The
value is calculated with all configured components in the system running at 100% utilization.
Typical, or actual, power draw is determined by the percent average server utilization of all
applications running on the server blades. This value is not just processor utilization but includes the
utilization of memory, hard drive and other system components. Therefore, typical power draws are
unique to each customer environment and are usually much lower than the maximum power
calculated by the sizing utility. Table 2 shows approximate percentages of the calculated maximum
power based on average utilization rates. For this table, average utilization rate is defined as the
average application utilization rate across all server blades connected to a specific power subsystem.
Table 2. General rules of thumb for correlating utilization rates to maximum power load
Average utilization rate Approximate percent of maximum power load
Idle – 65% utilization 60 – 75% of max. power
65 – 80% utilization 75 – 85% of max. power
99% utilization 90% of max. power
Rack-centralized power configuration options
Several options are available for configuring the HP BladeSystem p-Class 3U power enclosure. There
are two different p-Class server blade enclosures – the standard HP p-Class server blade enclosure
and the HP p-Class server blade enclosure with enhanced backplane components. The HP
BladeSystem p-Class 3U power enclosure can be configured for either of these blade enclosures or for
a combination of the two.
Upgrading the standard HP p-Class server blade enclosure
The standard p-Class server blade enclosure has been replaced by the HP p-Class server blade
enclosure with enhanced backplane components. However, the standard p-Class server blade
enclosure can be upgraded using the Server Blade Enclosure Upgrade Kit, which contains enhanced
backplane components and enables a field upgrade of a standard server blade enclosure. When
upgrading standard server blade enclosures that use mini bus bars, the dual-power input kit for mini
bus bars allows the mini bus bars to support a second power enclosure. This enables the power
subsystem to provide maximum power redundancy using the enhanced server blade enclosures.
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The Sizing Utility is available at http://h30099.www3.hp.com/configurator/calc/BL p-Class.xls
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