Twitter has issued an apology and an explanation of what caused the outage earlier this evening:
We are sorry. Many of you came to Twitter earlier today expecting, well, Twitter.
Instead, between around 8:20am and 9:00am PT [3:20pm and 4:20pm BST], users around the world got zilch from us.
By about 10:25am PT [5:25pm BST], people who came to Twitter finally got what they expected: Twitter.
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.
– Mazen Rawashdeh, Twitter Vice President, Engineering
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 acascading bug.
Instead, it was due to this infrastructural double-whammy.
We are investing aggressively in our systems to avoid this situation in the future.
On behalf of our infrastructure team, we apologise deeply for the interruption you had today.
Now — back to making the service even better and more stable than ever.