(Photo: Mobile Marketing)

Between 8:20 a.m. and 9 a.m., Twitter completely crashed, leaving many users devastated and distraught. We desperately cast about for answers in the bittersweet shelter of other social networks, begging our Facebook friends and our Tumblr followers for an answer to the long-lasting outage. An error page brought no relief: "Whole server runtime (in this case Ruby engine) is down and web server send raw code to client browsers," a helpful commenter attempted to clarify, but we still had no idea what % = reason actually meant. It was a rough 40 minutes.

The service came back up a few hours ago, but Twitter hadn't explained itself until now. So what happened? Was it a hacker attack? Olympic overload?

Turns out it was a total data center fail--doesn't have quite the same ring to it as "cascading bug," but we'll deal.

According to Twitter's VP of engineering, Mazen Rawashdeh:

The cause of today’s outage came from within our data centers. Data centers are designed to be redundant: when one system fails (as everything does at one time or another), a parallel system takes over. What was noteworthy about today’s outage was the coincidental failure of two parallel systems at nearly the same time.

I wish I could say that today’s outage could be explained by the Olympics or even a cascading bug. Instead, it was due to this infrastructural double-whammy. We are investing aggressively in our systems to avoid this situation in the future.

Seems like a totally understandable freak coincidence. Perhaps you'd like to retract your "Fuck You," Debby in Germany?

Apparently short a few G's.

In the run up to its recent IPO, a number of outlets reported that the daily deal giant Groupon was running short on cash. Over at the Motley Fool, Evan Niu noted that the company had $243.9 million in cash and equivalents at the end of September, compared with $465.6 million in accrued merchant payables, that is, the money they owed people who ran Groupon deals.

The company ended up raising $700 million, but according to a source familiar with its business, there still isn't enough cash on hand to make critical structural improvements the company needs to grow. Groupon is shelling out millions every month on hosting costs, and paying a premium to third parties. The company is very eager to construct it own data center, but simply can't afford it.

As ZDNet notes, Groupon's massive scale is a challenge and an opportunity. "Groupon’s growth—revenue, subscribers and merchants—is off the charts and under the hood rests on whale of an information technology story. In many respects, Groupon is the ultimate IT petri dish. In two years, it has grown from a company that could be run on a simple spreadsheet to one that needs systems spread across the globe.  Meanwhile, Groupon is a greenfield opportunity—there aren’t legacy systems dating back decades."

The company actually made a note of this in its IPO prospectus: "We have spent and expect to continue to spend substantial amounts on data centers and equipment and related network infrastructure to handle the traffic on our websites and applications. The operation of these systems is expensive and complex and could result in operational failures. In the event that our subscriber base or the amount of traffic on our websites and applications grows more quickly than anticipated, we may be required to incur significant additional costs."

You can see some of what Groupon had in mind on this job application the company put up for a Performance Engineer.