On Tuesday, many websites and services, including Medium, Slack and Business Insider, were either not working or working very slowly. It turns out, these websites, and many others, utilize Amazon’s cloud storage service S3, which suffered “high error rates” that day.
As Wired points out, “the internet is actually pretty brittle.”
To explain the outage, Amazon today issued a dense, technical statement. In it, the company says the issue stemmed from a programmer entering a command incorrectly. It’s scary to think that’s all it takes to bring down part of the internet. If you have the technical chops to understand it, here’s the full statement:
We’d like to give you some additional information about the service disruption that occurred in the Northern Virginia (US-EAST-1) Region on the morning of February 28th. The Amazon Simple Storage Service (S3) team was debugging an issue causing the S3 billing system to progress more slowly than expected. At 9:37AM PST, an authorized S3 team member using an established playbook executed a command which was intended to remove a small number of servers for one of the S3 subsystems that is used by the S3 billing process. Unfortunately, one of the inputs to the command was entered incorrectly and a larger set of servers was removed than intended. The servers that were inadvertently removed supported two other S3 subsystems. One of these subsystems, the index subsystem, manages the metadata and location information of all S3 objects in the region. This subsystem is necessary to serve all GET, LIST, PUT, and DELETE requests. The second subsystem, the placement subsystem, manages allocation of new storage and requires the index subsystem to be functioning properly to correctly operate. The placement subsystem is used during PUT requests to allocate storage for new objects. Removing a significant portion of the capacity caused each of these systems to require a full restart. While these subsystems were being restarted, S3 was unable to service requests. Other AWS services in the US-EAST-1 Region that rely on S3 for storage, including the S3 console, Amazon Elastic Compute Cloud (EC2) new instance launches, Amazon Elastic Block Store (EBS) volumes (when data was needed from a S3 snapshot), and AWS Lambda were also impacted while the S3 APIs were unavailable.
S3 subsystems are designed to support the removal or failure of significant capacity with little…