At approximately 7:45 Eastern time on Sunday March 22nd the myshopify.com server cluster experienced a Distributed Denial of Service attack (DDoS) causing our main firewall to become extremely slow. This slowness prevented our other backup firewalls from taking over. This attack resulted in the entirety of Shopify.com becoming unavailable. We were able to force data to the other firewalls but they too were immediately over run by the DDoS. It was not until we called on the admins of our data center to help us resolve this issue that we learned it was an DDoS on Shopify.
As of 10:35 EST Shopify.com is back up and running. We sincerely apologize for this downtime, and that this type of attack was able to take place.
Update #2 related to the first problems, many people started seeing the following error around 2:00 EST: Liquid error: s3.amazonaws.com temporarily unavailable. In many cases this lead to the admin being unavailable or the store front not to render right. This issue is now resolved as of 2:28 EST.
As you can imagine this has been an interesting day for us. We are taking steps to prevent it from ever being able to happen again and run a full analysis on the events. A truckload of new server hardware is already en route.