From the source
Vercel performed a full production failover of its core control-plane database from Azure West US to East US 2 on July 24, 2025, with zero customer impact.
The test followed two major Azure West US power failures in 2024 that had prevented critical write operations.
Preparation involved 57 staging failovers and revealed issues such as proprietary Cosmos DB clients lacking failover awareness and hardcoded delays that were subsequently reduced from five minutes to five milliseconds.
