The Boston Diaries

Monday, November 26, 2007

A little lapse in posting

Wow, a week has gone by without a post.

What happened?

Um … a bloggers strike … yea … that's it. The local Blogger Chapter #34 went on strike. You know how it is …

The Secret Temple (that's not so secret anymore)

Here, 100ft down and hidden from public view, lies an astonishing secret one that has drawn comparisons with the fabled city of Atlantis and has been dubbed “the Eighth Wonder of the World” by the Italian government.

For weaving their way underneath the hillside are nine ornate temples, on five levels, whose scale and opulence take the breath away.

Constructed like a three-dimensional book, narrating the history of humanity, they are linked by hundreds of metres of richly decorated tunnels and occupy almost 300,000 cubic feet—Big Ben is 15,000 cubic feet.

…

Indeed, the Italian government was not even aware of their existence until a few years ago.

But the “Temples of Damanhur” are not the great legacy of some long-lost civilisation, they are the work of a 57-year-old former insurance broker from northern Italy who, inspired by a childhood vision, began digging into the rock.

Via Instapundit, Eighth wonder of the world? The stunning temples secretly carved out below ground by “paranormal” eccentric

It's amazing what Oberto Airaudi has been able to accomplish, unseen, in thirty years of work.

Musings on high volume email servers and X-Grey, the greylist daemon

On Saturday, I bumped into Rob at a “After Thanksgiving Party” and we discussed the use of X-Grey at Negiyo, at least, those parts of Negiyo email that Rob helps to manage.

The code, as is, won't work with their setup. First problem, the sheer volume of email—something like 100,000 connections per second. These are fed through two load balancers and farmed out to about 100 servers, so each server is responsible for 10,000 connections per second. While I suspect X-Grey can handle 10,000 connections per second, the major problem are the load balancers—there's just no guarantee that the load balancers will be consistent on which machine they send the connection to.

For instance, we have some machine, on IP address 10.20.30.40 sending an email from alice@example.net to bob@negiyo.com. The load balancer will send that to server A, which doesn't find the tuple [10.20.30.40 , alice@example.net , bob@negiyo.com], stores it for later reference, and sends back “try again later.” Later, the machine at 10.20.30.40 tries sending the email again, only this time, the load balancer sends the connection to server B, which doesn't find the tuple, stores it, and sends back “try again later.” Lather, rinse, repeat until the sender gives up, or the load balancer manages to send the traffic to a machine that actually has the tuple stored.

There's just no way of knowing which server the load balancer will send the traffic to. So, we point all the servers to a single greylist server, which now has to handle 100,000 requests per second. Okay, so assuming X-Grey can handle that load (it's a real beefy box on a fat pipe), and given that we store greylisted tuples for six hours … carry the one … 2,160,000,000 tuples.

Blink.

Okay, now that I'm actually doing the math instead of sitting around in a comfortable chair listening to Rob while chowing down on turkey and stuffing, I find it rather difficult to believe that Negiyo is getting around 8½ billion emails per day—even a billion per day is stretching my credibility. The worst we get at The Company is 8 per second, with an average hovering around 1.4 (or 122,540 per day, which I calculated twice, using two different statistics that are recorded). More believable is 100,000 per hour (or even up to 1,000,000 per hour, which is 11 emails per second).

I'll have to get back with Rob on this …

Guerrillas clandestinely time their movement in Paris clock

Four members of an underground “cultural guerrilla” movement known as the Untergunther, whose purpose is to restore France's cultural heritage, were cleared on Friday of breaking into the 18th-century monument in a plot worthy of Dan Brown or Umberto Eco.

For a year from September 2005, under the nose of the Panthéon's unsuspecting security officials, a group of intrepid "illegal restorers" set up a secret workshop and lounge in a cavity under the building's famous dome. Under the supervision of group member Jean-Baptiste Viot, a professional clockmaker, they pieced apart and repaired the antique clock that had been left to rust in the building since the 1960s. Only when their clandestine revamp of the elaborate timepiece had been completed did they reveal themselves.

Via tryss, Undercover restorers fix Paris landmark's clock

And speaking of clandestine construction, what's up with the Europeans?