Tom Banta

By: Tom Banta on June 5th, 2019

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Questions You Need to Ask About Your Power Requirements

Colocation | Data Center Infrastructure

When an organization decides to migrate its IT infrastructure into a colocation data center, there are a lot of factors to take into consideration. Chief among them are often connectivity options and physical security, but given their impact on pricing, power requirements are often not far behind. In order to accurately assess their power needs, a potential colocation customer needs to answer a few (relatively) simple questions.

How Much Rack Space Do You Need?

The first big question when considering colocation is how much physical space the servers are going to occupy in a data center rack. A rack unit (U or RU) is a standardized measurement equal to 1 ¾ inches. Most components installed in a cabinet, such as servers, are between 1U and 4U high and 19 inches wide. A typical full-sized cabinet is 42U high, which is a little over six feet high.

When evaluating how much server rack shelf space colocated assets will require, everything depends upon the server size and type. Typical servers may take up between 1U and 4U, but blade server enclosures take up more space to accommodate the vertical blades. Since more blades can be installed vertically, however, they can offer substantial space savings in relation to the amount of computing power they deliver.

Determining the total amount of rack space needed, then, is a simple matter of measuring how many rack units the equipment being colocated takes up. Of course, calculating space is only part of the equation. Depending upon the type of servers being used, the equipment could have vastly different power requirements.

How Much Power Do You Need?

The amount of power colocated assets require is measured in kilowatts (kW) and can be calculated in a few ways. In many cases, figuring out how to calculate power requirements consists simply of checking the servers’ nameplates and adding up the total watts required to the total amount of power the hardware needs. If the wattage is not listed, the value can be derived by multiplying operating voltage times the current (amperes):

Watts = Voltage x Amperes (W = V x A)

To convert wattage to kilowatts, simply divide the total watts by 1,000. For an idea of how much power this colocated equipment will consume over a typical billing cycle, multiply kW by the number of hours (so 720 hours for a 30 day period). This will provide a rough estimate of kilowatt hours consumed, which can then be applied to local electrical rates.

So, if colocated servers require 4000 watts of power (or 4kW), they will consume 2880 kWh of electricity over the course of a month.

It’s important to remember these estimates will likely overstate the total power requirements. Manufacturers routinely overestimate how much power hardware utilizes and fail to account for the fact that equipment’s sustained draw is typically 80 percent of the rated maximum wattage. There is also a tendency to round off nameplate amperage to the nearest whole number, which can further distort power consumption estimates. The most accurate way to evaluate power needs is to test the server using a watt meter.

The power demands of this equipment will impact the type of power distribution units (PDUs) needed for the cabinet. A higher density deployment will require heavier power distribution equipment to accommodate the increased power. If a colocation facility doesn’t have cabinets with sufficient power capacity, they will need to spread the deployment across multiple cabinets, which could compromise performance and increase cooling costs.

What Are Your Future Power Needs?

Evaluating today’s power needs might seem like a challenge, but it’s also important to consider how those needs may change in the future. If a company is planning to scale significantly over the course of a year, it may make sense to base its power requirements on those future needs to ensure that any data center deployment will be able to accommodate growth. While colocation data centers are versatile and offer tremendous opportunities for organizations that need to scale quickly, space is often at a premium and failing to account for growth could result in missed opportunities.

While transitioning into a colocation data center opens up a world of possibilities in terms of connectivity and network architecture, organizations should always consider how to calculate power requirements before the migration takes place. By accurately assessing power requirements, they can better optimize their deployment and retain the flexibility they need to grow their business in the future without incurring unnecessary costs today.

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About Tom Banta

Tom is the Senior Vice President of Product Management & Development at vXchnge. Tom is responsible for the company’s product strategy and development.

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