This content is part of the Essential Guide: Colocated data centers uncut: Avoid these costly errors

Colocation facility selection requires careful planning

In part two of a series on choosing a data center colocation facility, find out how to compare features accurately.

In part one of this article on selecting a colocation facility, we discussed some of the main factors to consider before taking the plunge, and the first steps for making the right choice of provider. Now, we dive even deeper.

Selecting a colocation (colo) facility can be a confusing, frustrating process, and the wrong decision can send your data center down a costly path. Part of safeguarding against that fate is to establish solid processes for provider selection. Here's some guidance on comparing request for proposal (RFP) responses from providers and tips to avoid the most common pitfalls.

Normalizing responses

Colo providers differentiate offerings in confusing ways. The end result is often apples-to-oranges comparisons for customers, especially concerning the two largest cost components: rent and power. Standardize provider responses so you can make an accurate comparison.

Rent. Does the provider charge rent per square foot or per kilowatt? A 200 watt-per-square-foot facility is nearly twice as expensive to build as one that costs 100 W per square foot. We recommend comparing by cost per kilowatt of IT load, since you are buying compute capacity, not space, and power consumption tracks very closely to compute load.

Power. Here are five common methods for pricing power:

  • Circuit based: A "use it or lose it" approach, where most customers average 30% unused capacity.
  • Bulk kilowatt: A "use it or lose it" approach with less waste.
  • Metered IT load, plus cooling factor: The simplest and most straightforward approach.
  • Metered IT load, plus additional rent: A complicated mix of fixed and variable costs.
  • Metered IT load, plus computer room air conditioning (CRAC) load, plus cooling factor: A complicated method with the potential for double payment.

We recommend translating a provider's pricing structure based on your power configuration and circuit deployment.

Avoiding pitfalls

Don't buy the brand. Data center providers acquire competitors with different designs; they adjust designs based on building specifications or market variables and sometimes change design philosophies. These design variations often create divergent capabilities across a provider's property portfolio. Understand the specific property, and confirm that it meets your requirements.

Verify and inspect. RFP questions can be interpreted in many ways. Verify your requirements with visual inspections. Common problems include false promises of N+1 redundancy that can't be satisfied with a single generator, hot and cold aisles installed at 90 degrees (which exhausts hot air into a neighbor's server inlets) and water pipes installed directly above cabinets.

Maximize your options. Don't disqualify the best facilities by requiring power densities that exceed the densities of the providers in the market. Design options can mitigate density limitations.

Weight requirements according to importance. Loss of power for even one second can bring your environment down. Servers can operate even when temperature thresholds are exceeded. Both factors are critical, but power trumps cooling.

Examine the right of first refusal. We've seen expansion options presented to tenants before they've even moved into a data center. Include two or three expansion options in your lease.

Read the lease during RFP review. Review the lease early in the process to avoid insurmountable problems later.

Understand the cost of your requests. Requiring early termination rights without cause is a costly request and often ends negotiations with a provider.

Steve Gunderson is a principal at Transitional Data Services.

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