Facebook Outage Not a Hack, But Self Inflicted Wound

With rumors flying that Facebook was hacked yesterday, Facebook releases a statement explaining the 2.5 hour outage. It would appear that they were not hacked, but internal complications in responding to an error condition brought them down:

… Today we made a change to the persistent copy of a configuration value that was interpreted as invalid. This meant that every single client saw the invalid value and attempted to fix it. Because the fix involves making a query to a cluster of databases, that cluster was quickly overwhelmed by hundreds of thousands of queries a second. 

To make matters worse, every time a client got an error attempting to query one of the databases it interpreted it as an invalid value, and deleted the corresponding cache key. This meant that even after the original problem had been fixed, the stream of queries continued. As long as the databases failed to service some of the requests, they were causing even more requests to themselves. We had entered a feedback loop that didn’t allow the databases to recover. 

The way to stop the feedback cycle was quite painful – we had to stop all traffic to this database cluster, which meant turning off the site. Once the databases had recovered and the root cause had been fixed, we slowly allowed more people back onto the site…

Continued on Facebook.com.

4 thoughts on “Facebook Outage Not a Hack, But Self Inflicted Wound”

  1. Doh! Somebody’s gonna get an email….. lol

    At first I thought all that trolling I did on the “everybody draw mohamhead day” group had finally caught up with me 🙂

  2. Philo, I found this quote on Twitter:

    “Dear @facebook , My farmville cow died while your network was down. You owe me three magic beans!”

    So apparently your E-mail won’t be the only one that Facebook gets! 🙂

  3. heh heh, I saw something from the Oregon Public Schools:
    “Facebook goes offline, country pulls out of recession as worker productivity skyrockets..”(!) Priceless 🙂

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