Are you ready for 8Gb?
I just read an article on The Register saying that the Fibre Channel vendors will begin filling our Inbox's full of propaganda about 8 Gb switches and HBAs next year. Does more than 2% of the market really need that much bandwidth? I know I don't.
The only reason we began switching to 4 Gb switches was because they were cheaper than the 2 Gb model. We just began buying 4 Gb HBAs and until the 4 Gb port cards on my disk subsystems are cheaper than the 2 Gb model I won't buy those either. We just don't need it. I have one application that could even think about filling a 2 Gb pipe let alone a 4 Gb pipe. The vendors are really going to have to convince me with cost that I have to have 8 Gb. Good luck. 
December 19th, 2006 at 7:16 pm
You have to look at it from a Vendor standpoint though. If they don’t keep pushing speeds up, they’ll lose their ass to 10Gbe when it eventually drops in price. With 8Gb FC on the market, they’ll be fine. The overhead incurred with 10Gbe will most likely make it slower than 8Gb FC unless someone comes up with some pretty crazy fairy dust to sprinkle on that copper
December 19th, 2006 at 7:26 pm
On a side note – I recently read a comment to one of Jesse’s recent posts (http://www.sangod.com/?p=39) that 50u cabling is going to be a requirement for 8Gb FC. Might be worth keeping that in mind so that the eventual move to 8Gb FC will be smoother.
December 19th, 2006 at 8:56 pm
Totally pointless. 4Gb/s gives us nothing today. Look at 10Gb/s Cisco blades in the 95xx series – 4 ports per blade if my memory serves me right, based on 48Gb/s of blade bandwidth. With 48 port cards the ports are 400% oversubscribed at 4Gb/s (which you can’t configure them all to anyway). The issue is backplane bandwidth; only Brocade can offer 4Gb/s today non-blocking; the others have overpowered overheating oversubscribed (overpriced??) “offerings”. BTW, I don’t work for any switch vendor!
December 19th, 2006 at 11:53 pm
Chris:
Not true at all, the QLogic 9xxx series is completely non-blocking and expands up to 256 4Gb ports.
I can also tell you for a fact, video editing companies are eating up 4Gb hardware like gypsies at a food shelf.
December 20th, 2006 at 12:26 am
Brocade switches are non-blocking and are subscribed on a 1:1 basis. Cisco is the only company (that I know of) that believes it’s okay to oversubscribe a port.
December 20th, 2006 at 4:51 pm
That’s because cisco thinks that ethernet and FC are synonymous. While they do share a lot of characteristics, they’re definitely two very different beasts when it comes to oversubscription. Then again, it seems a lot of their customers find that acceptable, and if I could drive up profit margins that way I suppose I’d do the same thing
December 20th, 2006 at 7:24 pm
Snig, i have to update you on your statement that Cisco is the only one that does oversubscription.
McData's 6140 with QPM's (4port 4Gb/s) blades are oversubscribed as well, when you choose to configure them in burst-mode. If you configure them in full 4Gb/s ports, only two out of four ports are usable. Since we have no need for 4 Gb/s ports, we have no issues with this.
The 4Gb/s ports we have, are solely bought upon their price.
I'll go on Tims first comment, on the "vendors point of view".
I am not sure on the 50 micron cabling comment though. Given the current cabling specs, a 4Gb/s link on a 50 micron cable should not exceed a length of about 80 to 100 meters. On 8 Gb/s speeds, my estimate would be that the cabling should not exceed 40 to 50 meters. I some cases this could be insufficient. In our shop some cables runs get close to some maximums for 4 Gb/s.
December 20th, 2006 at 7:57 pm
c2: on the topic of 50u, I’m just going from what I’ve heard coming back from our engineering group on 8Gb FC. Things may change before product hits the street, but as it stands now (last I heard was ~3 months ago), you need 50u for 8Gb. We just setup a new lab and they ordered all 50u specifically because of that.
December 20th, 2006 at 8:47 pm
Thanks for the update c2olen.
December 20th, 2006 at 9:16 pm
Tim,
50u cabling will be sufficient in most cases. But just not for long hauls. A lab environment and most core-edge designed SAN’s will work fine on short 50u cabling.
To my opinion the 50u cables are easier to manage too, not “so” delicate.