On Sep 26, 2010, at 10:29 PM, Richard A Steenbergen <r...@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 <r...@e-gerbil.net> http://www.e-gerbil.net/ras > GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC) >
