On Sep 26, 2010, at 10:29 PM, Richard A Steenbergen <ras@e-gerbil.net> wrote:
On Sun, Sep 26, 2010 at 09:24:54PM -0400, Alex Rubenstein wrote:
And, not to mention that some vendors do it sometimes.
"The 9-slot Cisco Catalyst 6509 Enhanced Vertical Switch (6509-V-E) provides [stuff]. It also provides front-to-back airflow that is optimized for hot and cold aisle designs in colocated data center and service provider deployments and is compliant with Network Equipment Building Standards (NEBS) deployments."
A classic 6509 is under 15U, a 6509-V-E is 21U. Anyone can do front to back airflow if they're willing to bloat the size of the chassis (in this case by 40%) to do all the fans and baffling, but then you'd have people whining about the size of the box. :)
I would point out that it is quite possible to build a compact (say 4-5 U) front-back airflow platform if vendors were willing to pay to engineer a small midplane and leverage modular I/O cards in a single vertical arrangement. As an example, envisage an M10i with 8 single height PIC slots, rear mounted RE/PFE combos, and a top/bottom impeller. Same for a 72/73xx, or whatever platform you fancy. But would it make business sense? You'd lose rack space in favor of thermal efficiency. I think the push toward cloud computing and the re-emergence of big datacenters with far more stringent power and heat restrictions may actually drive such a move. I guess we'll see... C
It only took 298 years from the inception of the 6509 to get a front-to-back version. If you can do it with that oversized thing, it certainly can be done on a 7200, XMR, juniper whatever, or whatever else you fancy.
Well, a lot of people who buy 7200s, baby XMRs, etc, are doing it for the size. Lord knows I certainly bought enough 7606s instead of 6509s over the years for that very reason. I'm sure the vendors prefer to optimize the size footprint on the smaller boxes, and only do front to back airflow on the boxes with large thermal loads (like all the modern 16+ slot chassis that are rapidly approaching 800W/card). Also, remember the 6509 has been around since its 9 slots were lucky to see 100W/card, which is a far cry from a box loaded with 6716s at 400W/card or other power hungry configs.
Remember the original XMR 32 chassis, which had side to side airflow? They quickly disappeared that sucker and replaced it with the much larger version they have today, I can only imagine how bad that was. :)
-- Richard A Steenbergen <ras@e-gerbil.net> http://www.e-gerbil.net/ras GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)