Ascend Archive
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Re: (ASCEND) MAX 4000 + 56K modem cards = fire
Karl,
What can I say but your exactley correct, Same argument can be made on
the fans that were intially used in the Max. Overhead cost to go with
sleave bearing fans from the begining had to be only a few dollars
a box, But to Ascends defense they are learning from the mistakes made
in the past, Hopefully they have finished licking thier wounds and will
come up fighting.
Jason
On Tue, 9 Sep 1997, Karl Denninger wrote:
> On Tue, Sep 09, 1997 at 10:41:13AM -0500, Karl Denninger wrote:
> > On Tue, Sep 09, 1997 at 10:31:54AM -0500, Jake Messinger wrote:
> > > On Tue, 9 Sep 1997 ascend@digistar.com wrote:
> > >
> > > > I have a Davis Weather monitor (a weather station) inside the main server
> > > > room and looking at the temperature, the average is 62F, the peak being
> > > > 66F, the minimum being 61F. When the MAX 4000s died, the temperature was
> > > > well below 70F.
> > >
> > > What was the temp inside the max? Id suggest sticking a meat thermometer
> > > inside it.
> >
> > I'd like to note that a PM3, with a full load of modem cards, will continue
> > to operate if you *DISCONNECT* the single fan (which is really there to cool
> > the power supply) and it will NOT overheat in an average room under those
> > conditions.
> >
> > Control of overheating starts by being *very* careful about power consumption
> > to begin with.
> >
> > Remember that you pay for every watt consumed *twice* -- once to feed the
> > machine, and again to remove it from the room. There is no such thing as a
> > free lunch, and every watt you consume in a piece of computer hardware ends
> > up in the room as heat.
>
> Now I'm following up to my own posts.
>
> A *polite* hint to manufacturers:
>
> If you MUST build hardware which requires forced-air cooling to
> operate without damage (I fully understand that density and
> dissipation requirements sometimes require this) then you have
> an *OBLIGATION* to include temperature monitoring facilities in
> your harware which generate reportable status -- as well as an
> automated overtemp shutdown.
>
> Anything less should, IMHO, VOID your UL/CSA certification.
>
> CISCO does this in their larger router products (which will
> definitely croak if the fans fail or air intake is obstructed).
> ASCEND, at least in the MAX, does not (I don't know about the
> TNT). But they should. How much does a thermocouple and a
> small board to shut off the power supply cost? $10? C'mon
> folks.
>
> We had significant heat dissipation problems with the MAXes when we had
> them here. In fact, we had to change our racking plan and remove the
> side panels from both end racks in order to obtain rational flow-through
> temperature gradients through the chassis. With the end panels in place
> the operating temperatures of the MAXes were way beyond my comfort level
> for hardware of this type.
>
> IMHO the thermal engineering of the MAX with V.34 modem boards is marginal
> at best. Using DM12s was better than the original DM8s, but not by a lot.
>
> --
> --
> Karl Denninger (karl@MCS.Net)| MCSNet - Serving Chicagoland and Wisconsin
> http://www.mcs.net/~karl | T1's from $600 monthly to FULL DS-3 Service
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