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
OpenAI · 2026
Rapidly scaling online storage to serve over 1 billion ChatGPT users
OpenAI's Habitat storage platform grew from a Python client library over Cosmos DB into a central service handling 70M+ requests per second. The team ran many low-concurrency Python processes to keep asyncio delay down, switched aiohttp connection reuse from LIFO to FIFO to stop a metastable failure, used Envoy for connection fan-in, kept a deliberately simple NoSQL API, then rewrote the service in Rust.
70 million+ requests/sec1 billion+ weekly usersconnection poolingload balancingrate limitingPythonRustCosmos DB
Shopify · 2026
We replaced Redis with MySQL for inventory reservations—and it scaled
Shopify moved checkout inventory reservations from Redis to MySQL using one row per sellable unit, a bounded pool of 1,000 rows per item/location and SELECT ... FOR UPDATE SKIP LOCKED. The real ceiling was connections held by other checkout code: tagging SQL by business process and measuring hold time in ProxySQL found it, and the cleanup removed 50% of reads and 33% of transactions on the primary.
$5.1 million sales/minute (Black Friday 2025 peak)database migrationdual writesquery optimizationMySQLRedisProxySQL