In my post last week, I covered basic choices you'll face when selecting a type of colocation facility to host mission-critical enterprise workloads. Only hours after that posted to the Web, Hurricane Sandy slammed into the Eastern seaboard, leaving widespread flooding and wind damage in its wake. Particularly hard hit were northern New Jersey and New York City -- two of the most densely populated areas of the country as it relates to data center and colocation facilities.
Even as I write this, many of the largest data center facilities in Lower Manhattan are without commercial grid power, either due to extensive flooding or the spectacular ConEd substation explosion on the Lower East Side. In one case, a data center literally had to run a manual bucket brigade to lift diesel fuel to roof-mounted generators because the fuel pumps in the sub-basement were submerged in flood water -- an act that is nothing short of heroic. However, the fact that some data centers have emerged unscathed while others succumbed -- or had to fight tooth and nail to stay online -- provides an excellent object lesson in why it's so important to evaluate a prospective facility's preparedness for the unexpected.
Although a huge array of factors goes into making a good colocation center, including intangibles such as the quality of the people running the operation and the company's financial health, the most important qualities of any data center space are power, HVAC, staffing, and fire suppression. Read on for pointers on what to look for in each of these critical areas.
Power considerations
It's often said that power is the single most important commodity for any data center. That point cannot be overstated. In most cases, power infrastructure is what ultimately separates the various tiers of data centers, because it is typically the most expensive problem for data center operators to solve. To build a Tier 4 data center, you have to either be in a location where the commercial power grid provides true power supply diversity or be able to build your own power-generation capacity by implementing a cogeneration plant.
In both cases, the best data centers sport multiple, diverse building power entrances and internal distribution busways. If onsite step-down transformers are used, they will also be fully redundant -- typically to at least a 2N standard because these transformers are generally paired with the commercial power service entrances. However, even the best power grid will only take you so far -- a fact underlined by Hurricane Sandy. If the streets are flooded with water or a systemwide blackout occurs due to a power-supply problem, the facility will have to rely on its own power protection and generation capabilities.
First in line to react to a power outage is the uninterruptible power supply. In highly redundant Tier 4 facilities, these UPSes are deployed in 2N+1 configurations. Yes, twice the number of UPSes are required -- typically to pair with each of at least two diverse power routes and supplies -- and at least one UPS of extra capacity so that a UPS can be removed from service for maintenance without hurting availability. Because even the largest UPSes can keep a multimegawatt facility online only for seconds, the same redundancy rules typically apply to generators.