Cloudflare Frees 100TB of RAM With Smart Software Changes

Cloudflare just pulled off something remarkable in the tech world: they freed up 100 terabytes of RAM across their network without adding or replacing a single server.

The company powers 1.1.1.1, one of the world's most popular DNS resolvers that helps billions of people access websites faster. Behind the scenes, their system called Big Pineapple stores more than 250 billion DNS entries at any moment.

Engineer Sebastiaan Neuteboom and his team took a hard look at how each tiny piece of data was stored in memory. They found that every DNS cache entry was using 953 bytes of space, when it really only needed 420 bytes.

At massive scale, even a single wasted byte costs 250 gigabytes across Cloudflare's entire network. So the team got to work optimizing their Rust codebase with five key changes.

The biggest win came from removing unnecessary growth capacity in data containers. DNS records don't need to expand after entering the cache, but the old design kept metadata for expansion that would never happen. That fix alone recovered 15 terabytes.

The team also redesigned how DNS responses sit in memory, combining three separate lists into one streamlined buffer. They stopped storing duplicate domain names and switched to a variable-length format that wastes less space on small records.

The Bright Side

The results went beyond just saving memory. Insert speed jumped from 625,000 to 893,000 entries per second, while lookup times dropped from 828 to 670 nanoseconds.

Between mid-May and early July, memory use per instance fell from 9.3 gigabytes to 5.3 gigabytes. The system now runs leaner and faster than before the optimization work began.

Cloudflare isn't pocketing those savings or shutting down equipment. Instead, they're reinvesting the freed memory into larger DNS caches that can store more records locally.

Better cache performance means faster responses for users and less traffic hitting authoritative DNS servers around the world. It's a win for everyone who relies on the internet working smoothly.

This follows last year's successful rewrite of their request-handling system, also in Rust. As server memory becomes more expensive, smart software optimization offers a sustainable path forward for tech infrastructure.

Sometimes the biggest breakthroughs come not from buying more powerful hardware, but from using what you already have more wisely.