Why do we use facilities with EPO's?

Wed Jul 25 18:02:11 UTC 2007

Funny story about that and the EPO we have here...

We have chilled water cooling in our server rooms.  A couple of years
ago we told the facilities guys there was sand in the lines.  They
didn't believe us.  This went back and forth for a few months until
the lines finally ground to a halt.  They admitted sand was in the
lines.

The bring out an HVAC guy... he closes the valve, opens the pipe,
nothing comes out.  He **opens** the valve, nothing comes out.  He
whacks on the pipes with a wrench, all the sand and lots of water come
out very fast.  By the time I got down there, the ceiling tiles were
drenched and looked more like sponges.  Half the room was soaked.

That would be a good reason to have an EPO right there. :)

j

On 7/25/07, Leo Bicknell <bicknell at ufp.org> wrote:
>
> I was complaining to some of the power designers during the building
> of a major facility that the EPO button represented a single point
> of failure, and effectively made all of the redundancy built into
> the power system useless.  After all, what's the point of having
> two (or more) of anything, if there's one button somewhere that
> turns it all off?
>
> What I found interesting is that a single EPO is not a hard and
> fast rule.  They walked me through a twisty maze of the national
> electric code, the national fire code, and local regulations.
> Through that journey, they left me with a rather interesting tidbit.
>
> The more "urban" an area the more likely it is to have strict fire
> codes.  Typically these codes require a single EPO for the entire
> structure, there's no way to compartmentalize to rooms or subsystems.
> However in more rural areas this is often not so, and they had in
> fact built data centers to code WITHOUT a single building EPO in
> several locations.  That's to say there was no EPO, but that it may
> only affect a single room, or even a single device.
>
> 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?
>
> --
>        Leo Bicknell - bicknell at ufp.org - CCIE 3440
>         PGP keys at http://www.ufp.org/~bicknell/
> Read TMBG List - tmbg-list-request at tmbg.org, www.tmbg.org
>
>

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Thanks,
j