How to move nix store to external drive on macos?

abathur · June 8, 2022, 12:39am

While I haven’t tried it myself, IIUC a symlinked store can cause problems with some software. But the store volume doesn’t have to live on the same drive as /.

If starting over isn’t prohibitive, it’s probably easiest to follow the uninstall instructions (Installing a Binary Distribution - Nix Reference Manual) and then set the appropriate variables to specify a different disk before installing:

github.com

NixOS/nix/blob/b2dea231cf61d8d10cef89991571f57976b77f06/scripts/create-darwin-volume.sh#L64-L71


      
          # make it easy to play w/ 'Case-sensitive APFS'
          readonly NIX_VOLUME_FS="${NIX_VOLUME_FS:-APFS}"
          readonly NIX_VOLUME_LABEL="${NIX_VOLUME_LABEL:-Nix Store}"
          # Strongly assuming we'll make a volume on the device / is on
          # But you can override NIX_VOLUME_USE_DISK to create it on some other device
          readonly NIX_VOLUME_USE_DISK="${NIX_VOLUME_USE_DISK:-$(root_disk_identifier)}"
          NIX_VOLUME_USE_SPECIAL="${NIX_VOLUME_USE_SPECIAL:-}"
          NIX_VOLUME_USE_UUID="${NIX_VOLUME_USE_UUID:-}"

If starting over is prohibitive, it’ll be a little more DIY–but there’s inevitably some way to duplicate the existing volume to a new disk and then update /etc/fstab and /Library/LaunchDaemons/org.nixos.darwin-store.plist to specify the new volume’s UUID (fair warning: this will be more complicated if you’re using FileVault).