FUD at 10 Gigabits Per Second

At my last job, I had to work with InfiniBand. Believe me, this did not lead to an enduring love of IB. Before InfiniBand, I had worked with Fibre Channel and seen how overburdened it was with every vendor’s favorite feature or format or protocol variation, often with some little bit hidden somewhere to tell you which of several possible (and mutually incompatible) behaviors you were expected to exhibit in response. Compared to IB, FC is a model of streamlined simplicity. How’s that for scary? Nonetheless, now that all those thousands of person-hours have been poured into it, IB does actually manage to deliver somewhat on its original promise of high bandwidth and low latency at low cost.

So along comes 10-gigabit Ethernet (10GbE), which is so many levels removed even from the thing that people called Ethernet after original Ethernet had been dead and buried that nothing remains but the brand name. It seems that some folks are sure it’s going to displace IB as a cluster interconnect Any Day Now. Hitching themselves to that belief, they’ve started flinging FUD about IB’s “misleading” bandwidth numbers. Here’s one of the more egregious examples.

We will tear this black cable bandit down to size one claim at a time. First they assert that it’s 20Gbps, how about 12Gbps on it’s best day with all the electrons flowing in the same direction. Infiniband employs what is know as 8b/10b encoding to put the bits on the wire. For every 10 signal bits there are 8 useful data bits. Ethernet uses the same method, the difference is that Ethernet for the past 30 years has advertised the actual data rate while Infiniband promotes the 25% larger and useless signal rate. Using Infiniband math Ethernet would then be 12.5Gbps instead of the 10Gbps it actually is. So using Ethernet math Infiniband’s Double Data Rate (DDR) is actually only 16Gbps and not the 20Gbps they claim.

Apparently, according to “10GbE math” 16Gb/s is less than 10Gb/s. Spare me. DDR IB is at approximate price parity with 10GbE, and still 60% faster than 10GbE – with QDR products already available. How does that make 10GbE the superior choice, again? Wait, you say. Those are only nominal bandwidths, right? True enough, and just as true for 10GbE as for IB. It would be a little disingenuous to point out that IB doesn’t really achieve 16Gb/s except “on it’s best day with all the electrons flowing in the same direction” without also pointing out that 10GbE is subject to the same effects (and the vast majority of cards according to 10GbE.net’s own price lists aren’t even physically capable of more than 13Gb/s across two ports).

The writing style on 10GbE.net is strikingly similar to that of a certain Cisco employee. Instead of launching all this FUD from behind a screen of anonymity, would it be too much to ask that the author show a little more honest about his associations? When he can show repeatable, verifiable results indicating that DDR IB doesn’t still trounce 10GbE at the same price point, then we can have a real discussion about cluster interconnects.

Random Thoughts on the Gaza Situation

(1) Attacks that target civilians, or result in excessive civilian casualties, are wrong regardless of who launches them.

(2) Hiding military actions behind civilian facilities or institutions, and particularly religious or humanitarian ones, is wrong for the same reasons.

(3) Yes, we do expect that a nation which prides itself on being advanced both technologically and socially, and which is much richer, will make greater efforts to protect civilians.

(4) If people see that peace brings only economic and even literal starvation, of course they’ll try something besides peace. What nation or group, including non-Palestinian Israel, would behave any differently under siege or blockade? What nation or group even should behave differently?

(5) Economic warfare is not morally superior to the literal kind, and breaking an economic cease-fire is no more acceptable. It’s just a coward’s way of provoking a response (see previous point) that the gullible will more easily recognize as warlike.

(6) There is no way that any Israeli military action short of a full occupation down to the city-block level (at least) will destroy Hamas’s ability to launch rockets into Israeli territory. If Israel denies that such an occupation is their intent (as they seem to be doing) then they admit they have some other intent.

(7) The only entity that might be capable of stopping Hamas’s rocket attacks is Hamas, and to do that they must have some reason to believe that the effect of ceasing the attacks will be a tolerable situation. If the situation will be intolerable even when they stop, they won’t stop.

My policy prescription is simple, and well known from game theory: it’s called Tit For Tat. While rocket attacks continue, the siege continues (and vice versa). When rocket attacks stop, the siege stops (ditto). Excessive retaliation or excessive concessions on either side fail to achieve any kind of equilibrium. In the face of such, each side will use whatever form of leverage it has to get whatever it can. Peace without justice never lasts. Those who perpetuate injustice, then, cannot escape the moral burden of perpetuating war.

Random Amy-Blogging

The other night, Amy said she had something stuck on one of the “stabs” of her fork. We knew exactly what she meant.