The worst thing you can do in tech is claim something positive or negative about some technology without anything to back it up. Ever since UCS was first brought to market, other blade vendors have been quick to point out any flaw they can find. This is mostly because their market share of the x86 blade space has been threatened and in some cases (IBM & Dell) surpassed by UCS.
One of the claims that I’ve heard while presenting UCS is that the major flaw with the architecture makes switching between to blades inferior to the legacy architectures that other hardware vendors use. You see, (they told me) in order for one UCS blade to communicate to another UCS blade you have to leave the chassis, go into the Fabric Interconnects (that could be all the way at the top of rack, or even in another rack), and then come back into the chassis. This must take an eternity.
Network traffic from one blade to another in the same chassis is called “East-West” traffic because the traffic doesn’t leave the chassis. (Picture it going sideways) where as “Nort-West” traffic is network traffic that leaves the chassis and goes out to some other end point that doesn’t reside in the chassis. The widely held belief was that UCS was a a huge disadvantage here.
After all, every other blade chassis on the market has network switches that sit inside the chassis and *must* be able to perform faster than UCS. For a while now, I’ve wondered how much latency that adds. Because, frankly, I thought the same way they did. Surely the internal wires must be faster than twinax cables.
But science, that pesky disprover of legacy traditions and beliefs, has finally come to settle the argument. And in fact has turned the argument on its head. The east-west traffic inside UCS is faster than the legacy chassis.
The full blog can be read here. There’s a link to a few great papers on this site that show how the measurements done.
Plus one for the scientific method!
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