Abstract; Introduction; Key Power Parameters; Input Line Voltage - HP ProLiant BL280c - G6 Server Introduction Manual

Abstract

With power requirements of computing equipment increasing and the cost of energy rising, IT
organizations need accurate estimates of power and cooling requirements for designing and
expanding data centers. HP has created the HP Power Advisor utility to provide more accurate and
meaningful estimates of power needs for HP ProLiant BL, DL, and SL systems so that IT infrastructure
designers can determine the most efficient hardware configuration. This technology brief identifies
factors affecting power requirements, explains how the Power Advisor works, and provides an
example of how it can be used.

Introduction

As information technology evolves and system density increases, systems housed in a single rack can
now consume the amount of power once required for several racks. Effective sizing of a compute
infrastructure while managing IT costs requires realistic estimates of current and future power and
cooling requirements. Accurately estimating the power consumption of a server rack can define power
distribution requirements at the rack level and can be the starting point for estimating the total power
consumption and cooling needs for a data center.
The HP Power Advisor utility is a tool for calculating power use of the major components within a rack
to determine power distribution, power redundancy, and battery backup requirements for computer
facilities.
This document assumes that readers are familiar with basic power concepts and HP ProLiant servers.

Key power parameters

Determining total power needs for a data center requires consideration of the key parameters
described in this section. More details about these parameters are available in the white paper titled
"Power Basics for IT Professionals" downloadable at
http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01234421/c01234421.pdf .
This paper does not discuss other signification parameters such as system serviceability and
scalability.

Input line voltage

Input voltage may be low-line or high-line voltage depending on what is available at the data facility.
Low-line voltage [100 – 120 volts alternating current (VAC)] is the standard for AC wall outlets in
North America. High-line voltage (200 – 240 VAC) is used in other parts of the world but is also
increasingly common in North American data centers. Most HP ProLiant servers accept a line voltage
in the 100- to 240-VAC range.
IT equipment designed to use either low-line or high-line voltage typically consumes less power and
generates less heat when operating off high-line voltage, which reduces the strain on cooling systems.
Some systems may actually require high-line voltage to meet maximum performance specifications.
Facilities may distribute AC power as single- or three-phase. Three-phase high-line power (such as
3-phase 208 VAC) is more efficient and recommended for systems requiring three kilowatts of power
or more.

Device VA rating

Apparent power is the total amount of power a device requires from the facility AC feed and is
measured in volt-amperes (VA). Knowing the total amount of VA for all active components in a system
helps data center planners determine the types and quantities of power distribution units (PDU) and
uninterruptible power supplies (UPS) needed for a given rack configuration.
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