01
Nov
11

Moving Beyond the Tier Rating

http://www.datacenterknowledge.com/archives/2011/10/31/facebook-cuts-back-on-generators-in-sweden/

This is an interesting article about an emerging resiliency strategy for large scale IT operations.  If you read through the Tier guidelines from the Uptime Institute, you’ll note that for the two upper tiers (more resilient with respect to downtime) that generator plants are considered the primary power source for the building, and that all other utility feeds are just lagniappe.  Well, what happens when those utility feeds are more reliable than a generator plant?

There is a whole series of events that must occur in the proper order to ensure that from the time a utility feed is dropped and gens are brought online, IT processes are preserved.  This is a very complex process and it is why we commission data centers.  We want to be sure that these backup systems come online without a hitch.  However, there are so many parts that must work properly, there exists the real possibility of failure.  To give you an idea in basic terms, the sequence might go something like this:

1. The utility feed goes down

2. A static switch at a UPS throws over to battery or flywheel power temporarily

3. Generators are brought online

4. Some kind of switch gear switches the power over to generator from failed utility

5. Static switch at UPS switches back over to primary feed

The equipment that is installed to make this happen is very, very expensive.  The generators can easily run into the 6-figures for each set, and all of the required switchgear and UPS modules constitute a substantial part of the cost of the project.  They can also carry substantial maintenance costs.  The other factor here is that a company with redundant processes across the globe can afford to allow downtime at any given facility.  In this way, it’s a bit like a car rental business in that there is no need for insurance, because having a whole fleet of cars IS the insurance.  The most telling part of the article is the last section, where they rightly point out that this would be courting disaster for a smaller operation that is more critical to a company’s function.

In the case of the power grid across the pond, to not have an outage in nearly 30 years is nothing short of amazing!  The Facebooks and Googles of the world appear to have transcended the world of tier ratings in a big way, and now they enjoy a competitive advantage with their lower cost facilities.

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