Simon Willison’s Weblog

Slashing Data Transfer Costs in AWS by 99% (via) Brilliant trick by Daniel Kleinstein. If you have data in two availability zones in the same AWS region, transferring a TB will cost you $10 in ingress and $10 in egress at the inter-zone rates charged by AWS.

But... transferring data to an S3 bucket in that same region is free (aside from S3 storage costs). And buckets are available with free transfer to all availability zones in their region, which means that TB of data can be transferred between availability zones for mere cents of S3 storage costs provided you delete the data as soon as it’s transferred.