On Thu, 20 Oct 2011, Luke S. Crawford wrote:
On Thu, Oct 20, 2011 at 04:52:57PM -0400, Doug Hughes wrote:
On Thu, Oct 20, 2011 at 3:08 PM, David Bronder <[email protected]>wrote:
Luke S. Crawford wrote:
I've been mounting switches backwards forever; I mean, the ports are on
the back of the servers, right? it only makes sense. Now, normally,
I put it at the top of the rack and it works fine; excess heat gets
sucked out through the fan at the top of the rack.
Some switch vendors have models now that have the airflow going in the
opposite direction, suitable for mounting in server racks, or that even
have reversible airflow so you can choose. Something to look at for
new switch purchases.
What David said. Force10, Arista, Blade, and others make switches that you
can just get the reverse power and fan modules and you're set. Big win.
(that's what we do)
you're not doing your switch any favors by letting it suck hot air into
itself, regardless of what you end up doing with the exhaust (even though
switches can typically handle higher ambient).
Hm. thanks. yeah, I'll get one that exhausts properly next time I buy
switches.
note that if you are trying to save money, most systems will let you
flip the fans without too much effort (or at least all the ones not inside
the power supply). If you are buying name brand 1u systems you will have
more problems as the airflow inside them is pretty carefully engineered,
but for whitebox systems and networking gear it's usually not too hard.
Daivd Lang
For now, like someone else said, if the heat from a switch cooks
the server, that server probably needs to be replaced anyhow. I tried
to put a 115w socket C32 chip in a 1u with weak cooling (a supermicro sc811)
and, well, it passed burn in, but only 'cause I only fail things out of burn
in if they crash or if they fail a test like memtest. It got hot - I
should fail things out of burn in if the CPU temp gets too high.
The co-lo I'm in (14th floor of market post tower in san jose) does something
kinda interesting with the cooling; they actually blow cold air down the
hot row. I asked my reseller about it, thinking some idiot just mis-labeled
the hot row and the cold row, and he said that this was 'optimal airflow'
I mean, the place is cold even in the cold row (which is warmer than the
hot row) so I'm not complaining too much, but it sure seems wrong to me.
(though, it should help some with this particular problem.)
I hear that serious datacenters isolate the hot row from the cold row and
just exhaust hot row air to outside. I imagine the isolation takes a bit
more effort from the people managing the racks than you can expect in
a multi-tenant setup, which is why all the co-los I've seen are
essentially mixed-air, though they do only spray the cold air down every
other row and the servers are stacked accordingly.
Meanwhile, I'm going to put this 115w chip in a 2u or 3u chassis with a lot
more fans and a much larger heatsink, and I'm going to update my burn-in
procedures so that I don't put iffy stuff into production. There's no
reason to skimp on cooling fans.
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