How Cloudflare saved 100TB memory in DNS services

Cloudflare reduced memory consumption in its DNS infrastructure by 56% through five targeted optimizations to its Big Pineapple platform's cache system. By restructuring how 250+ billion DNS cache entries are stored - replacing growable vectors with fixed-size boxes, shrinking metadata fields, and better aligning data structures - each entry now requires significantly less memory. These Rust-level changes cumulatively saved approximately 100 terabytes of memory across Cloudflare's global fleet while simultaneously improving performance: insert throughput rose 43% and lookup latency dropped 19%. The optimizations are particularly impactful for locations handling EDNS Client Subnet queries, where multiple response versions must be cached.