I need some help reducing the size of /nix. I have been through the storage optimization article in the wiki, and have ran garbage collection, with and without root privileges, as well as nix-store --optimise, but /nix is still 140GB which seems far too much.
If you’ve done a lot of updates without rebooting, it’s possible the old running processes are keeping old store paths alive from the GC. Nix checks the executables and environment variables of running processes to avoid GC’ing anything they need. Just a guess.