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Re: Why do we use facilities with EPO's?

  • From: Brandon Galbraith
  • Date: Wed Jul 25 15:40:12 2007
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On 7/25/07, Leo Bicknell <[email protected]> wrote:

The more "urban" an area the more likely it is to have strict fire
codes. 

<snipped>

If they can be avoided, why do we put up with them?  Do we really
want our colo in downtown San Francisco bad enough to take the risk
of having a single point of failure?  How can we, as engineers, ask
questions about how many generators, how much fuel, and yet take
for granted that there is one button on the wall that makes it all
turn off?  Is it simply that having colo in the middle of the city
is so convenient that it overrides the increased cost and the reduced
redundancy that are necessitated by that location?


We put up with EPOs for the same reason we put up with water-based fire suppression systems. Safety. When my firefighter buddy needs to cut through a wall in a data center, she better damn well be sure she can kill power to the entire area before she potentially cuts through 400-500V feeds in the walls. Hence, the EPO.

Now, I know you referred to a single EPO for the entire facility, and how that's akin to doing brain surgery with a sledgehammer. Perhaps someday someone will come up with a more surgical method for ensuring power is removed from the areas it needs to, while other unaffected areas can continue functioning. Until that point though, I prefer we err on the side of caution and value someone's life over business continuity.

Almost forget. You mentioned more "urban" areas require the master EPO being easily accessible in the facility. I don't know what gets more urban than the San Fran area.

-brandon