Emerson DI-STRIP, MPH2 White Paper
Considerations for a Highly Available Intelligent
Rack Power Distribution Unit
A White Paper on Availability
Introduction
Data centers are currently undergoing a period of great change. Data center managers are struggling to keep pace with growing
capacity needs while working under the constraints of tightened budgets and energy efciency initiatives and the challenges
presented by new technologies such as virtualization and cloud computing are transforming
As data center environments become more dynamic and complex, many organizations are taking a more proactive approach
to management and gaining better control of their data center operations so they can maintain or improve availability in
increasingly dense computing environments while reducing costs and boosting efciency. One area of improvement is inside
the rack with the growing importance of intelligent Rack Power Distribution Units (rack PDUs).
As the last link in the power chain delivering critical power to IT loads, intelligent rack PDUs are a strategic asset for achieving
high availability through elevated levels of responsiveness to change in data center capacities and densities. The emergence of
data center infrastructure management (DCIM) is further increasing the role of the intelligent rack PDU within the data center.
Data center managers are taking advantage of the benets provided by the technology, including access to rack-level and IT
equipment power consumption, visibility into rack-level environmental conditions, the ability to directly control power to IT
equipment and rack-level capacity and power management.
This white paper discusses the considerations that need to be made when investing in intelligent rack PDUs to ensure that they
do indeed provide a high availability solution.
Five aspects of a high availability design for Intelligent Rack PDUs include:
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Reliability
2
Functionality
3
Fault Tolerance
4
Maintainability
Adaptability
5
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Reliability
Intelligent rack PDUs (Figure 1), offering exible and
comprehensive remote management and real-time
monitoring capabilities, can provide the best view of IT power
consumption and rack operating conditions. However, while
these new rack PDUs offer advanced capabilities, they are not
much use if their core function is compromised or impeded:
providing basic power distribution in any circumstance. There
are a number of factors that should be considered to help
ensure the primary function of intelligent rack PDUs.
Figure 1. Today’s intelligent and adaptive rack
PDUs provide value beyond just power distribution,
enhancing business agility, efficiency and availability.
High Temperature Rating
Given their location at the back of the rack toward the
hot-aisle, rack PDUs are exposed to some of the harshest
temperatures found in the data center. (Figure 2) In this
location, it is fairly common to see temperatures of at least
122 degrees Fahrenheit (50 degrees Celsius). As power
densities continue to increase and more organizations
consider increasing the temperature in the data center to
reduce energy consumption costs, these temperatures are
only expected to rise. It’s important that intelligent rack
PDUs are rated to withstand a temperature of 131 degrees
Fahrenheit (55 degrees Celsius) or higher.
Figure 2. Located at the back of the rack toward the
hot-aisle, rack PDUs can be exposed to temperatures
exceeding 122 degrees Fahrenheit (50 degrees Celsius).
Low Idle PDU Power Consumption
As organizations invest in higher density IT equipment, the
number of components contained inside a rack PDU has
increased in order to provide higher levels of intelligence.
However, the overall form factor has remained relatively small.
It is important to realize that higher power consumption of the
rack PDU itself leads to higher internal stress. The amount of
heat dissipation within the rack PDU is determined by its idle
power consumption. If the idle power consumption level is
lowered, the heat dissipation within the rack PDU is lowered.
Idle power consumption should be an important consideration
especially for Switched rack PDU designs, which provide the
ability to turn on, turn off or recycle power to connected IT
equipment through the use of relays at every outlet. Idle power
consumption is generally not a specication put out by vendors
and hence should be requested.
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