Data Center Handbook

29Rack PDU for Green Data Centers

Ching-I Hsu

Raritan, Inc., Somerset, NJ, USA

29.1 Introduction

The rack power distribution unit (PDU) is emerging from obscurity. As the last link of the elaborate data center power chain, the traditional role of the rack PDU has been to deliver stable, reliable, and adequate power to all the devices in the rack or cabinet—servers, storage, network equipment, etc., which are plugged into it. And while it provides the electrical heartbeat to all the systems that run the critical applications that support the operation of the business (or that, in some cases, are the business), it was often considered a simple commodity—just a power strip. Typically, IT merely told facilities how much power was needed, based on device nameplate specs and often with redundancy, so there was plenty of headroom and minimal risk of downtime. Little thought was given to efficiency or what other value a rack PDU could provide.

That was yesterday. Over the past few years, system availability has become a “given,” and now, data center management attention is being focused on operational costs, efficiency improvements, and resource optimization. With the annual expenditure for powering the average data center surpassing the cost to purchase the equipment (ITE) itself, the use (and waste) of energy is now targeted as a priority. And beyond the actual cost to power the data center, there are the related issues that impact both current operations and future expansion—for ...