NixCon 2025

Styx: Faster substitution, less disk space
2025-09-06 , Aula

I pushed a simple question—how fast can I make NixOS updates—way too far, and came up with something slightly crazy.

The result combines various technologies to deduplicate data in a Nix store both on disk and over the network, add differential compression, and also enable on-demand fetching, without compromising system performance.

I'll describe the architecture of the system, trade-offs, some performance numbers, and a quick demo.

Nix enthusiast