A Quick Primer on Data Center Tier Classifications

Today, a number of companies are either consolidating their data centers or implementing new data center projects. Their decisions are often based on the appropriate "tier level" of the IT facility. The tier level is determined by an industry standard classification system for infrastructure performance. A four-tier system rates a facility's ability to support uninterrupted operation of its data processing activities.

The tier classification model provides an academic and objective benchmark that helps describe and compare the functionality, capacity, and cost of data center infrastructures. At times, the drive to align the uptime of the IT facility with the business becomes bogged down in focusing on tier levels. Other factors beyond tier level compliance can impact uptime performance. In this paper, we will first review data center tier levels, then comment briefly on what is and is not critical to tier level attainment, and conclude with some pragmatic advice about facility assessment.

The tier classification system measures the performance of a site's operating infrastructure, which includes power, cooling, emergency backup, and fi re suppression. The power and cooling capabilities of a facility are delivered by its Mechanical, Electrical, and Plumbing (MEP) infrastructure. This whitepaper discusses the following tiers:

• Tier-1 Basic Data Center Infrastructure
• Tier-2 Data Center with Redundant Capacity Components
• Tier-3 Concurrently Maintainable Data Center
• Tier-4 Fault-tolerant Data Center

ABOUT SWITCH AND DATA Switch and Data is a premier provider of network-neutral data centers that house, power and interconnect the Internet. Leading content companies, enterprises and communications service providers rely on Switch and Data to connect to customers and exchange Internet traffic. Switch and Data has built a reputation for world-class service, delivered across the broadest colocation footprint and richest network of interconnections in North America. Switch and Data operates 34 sites in the U.S. and Canada, provides one of the highest customer satisfaction scores for technical and engineering support in the industry, and is home to PAIX® — the world's first commercial Internet exchange.