OpenAI · 2026
Rapidly scaling online storage to serve over 1 billion ChatGPT users (Part II)
OpenAI's Habitat storage platform went from one shared Azure Cosmos DB container, to dedicated single-tenant containers that pushed capacity planning onto every product team, and back to a shared container by default once Azure added hot-key throttling, request-priority QoS and a new serverless mode where each physical partition scales to 10K RU/s and splits on RU usage. After failover and failback outages in late 2024, OpenAI and Azure now co-own testing and monitoring. Replicating small latency-critical datasets widely, a Valkey lookaside cache invalidated through the Cosmos DB change feed, and a Rust rewrite of the proxy cut global read p50 from about 120 ms to about 10 ms.
1B+ users across 40 regions500+ PB served by Habitatmulti-tenancyhot key throttlingCDC cache invalidationAzure Cosmos DBValkeyKafka