Data Center Capacity: Getting the Most from More
When an enterprise needs additional data center capacity, there are three fundamental options: existing site expansion, co-location and cloud services. Which option is best? The answer lies in understanding the balance of how critical the data center is to the business and what the fully loaded cost of supporting the application is. Few companies have good data or metrics on either. In fact, strategic decisions regarding the criticality of infrastructure are key — and these decisions are driven not by technology but by business requirements.
Data center risk assessments are often limited to operational risk, which is primarily linked to uptime. Uptime is frequently measured by the number of "nines" or the designation of a Tier level. However, hitting a targeted level of uptime is only one aspect of managing data center risk. To make prudent decisions about data center expansion, companies must understand the role performed by their data centers in the value chain of IT services.
This is why it is important to start the planning phase with an analysis of the business needs. ITIL, a business-model approach to IT services, makes the case very well: When IT services are aligned with and supportive of the core business processes, technology can be used to facilitate business change, transformation and growth.
Decision-makers can use the business case for IT expansion to identify requirements for system performance, security and reliability. In the planning phase, it is important to analyze the application requirements, in particular, the ability of the existing application architecture to operate in a decentralized environment. Planners also should consider the strategic business implications of decentralization, including the availability of resources to manage and operate multiple sites. Other critical issues include network latency; loss and recovery time of applications, data and services; tax and jurisdictional concerns; and legal and regulatory issues.
This strategic approach to planning enables decision-makers to rightsize the facility based on business needs. It avoids the tendency to overbuild based on a perceived need for, say, a Tier IV data center of N+2 or 2N and 300 watts per square foot because that is the "state of the art."
Here's a look at the advantages and disadvantages of each expansion option.