How the Baseten Delivery Network (BDN) makes cold starts fast

Introduced the Baseten Delivery Network (BDN), an opt-in weight delivery system for model deployments. BDN reduces runtime dependency on upstream providers by mirroring model weights into securely managed storage at deploy time. It caches weights across a three-tier hierarchy: node-local disk, an in-cluster peer cache backed by a consistent hash ring, and mirrored origin. BDN coordinates downloads to ensure fast cold starts during scale events and reduces costs by offloading weight transfer from billable GPU time and minimizing egress costs through deduplication of unchanged weight data. The system addresses brittleness in weight transfer at scale by mitigating slow pulls, upstream fragility, and thundering herd issues through its layered caching and push-time mirroring approach.