Why do we use facilities with EPO's?

Wed Jul 25 18:11:54 UTC 2007

On 7/25/07, Leo Bicknell <bicknell at ufp.org> 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
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