Keep Your Applications Running While AWS Is Down

Author here. AWS’s recent us-east-1 outage inspired us to share our approach to geo-replication with Restate.

The core idea: geo-replication should be a deployment concern, not something you architect into every line of application code. You write normal business logic, then configure replication policies at deployment time and let Restate handle the rest.

The configuration is straightforward: `default-replication = "{region: 2, node: 3}"` ensures data is replicated to at least 2 regions and 3 nodes. This ensures that your apps can tolerate a region outage or losing two arbitrary nodes while staying fully available. Behind the scenes, Restate handles leader election, log replication, and state synchronization. We use S3 cross-region replication for snapshots with delayed log trimming to ensure consistency.

We tested this with a 6-node cluster across 3 AWS regions under 400 req/s load. Killing an entire region resulted in sub-60-second automatic failover with zero downtime and no data loss. Only 1% of requests saw latency spikes during the failover window. Once nodes in us-east-1 were no longer running, P50 latency increased when replication shifted from nearby us-east-1/us-east-2 to distant us-east-2/us-west-1.

Happy to answer technical questions or discuss tradeoffs!