At last week’s ACM Symposium on Operating Systems Principles (SOSP), my colleagues at Amazon Web Services and I won a best-paper award for our work using automated reasoning to validate that ShardStore — our new S3 storage node microservice — will do what it’s supposed to. Amazon Simple Storage Service (S3) is our fundamental object storage service — fast, cheap, and reliable. ShardStore is the service we run on our storage hardware, responsible for durably storing S3 object data.