add speedtest filesystem helper

utilities/nixos-installers/flake.lock

@@ -982,16 +982,16 @@
     },
     "stable": {
       "locked": {
-        "lastModified": 1764939437,
-        "narHash": "sha256-4TLFHUwXraw9Df5mXC/vCrJgb50CRr3CzUzF0Mn3CII=",
+        "lastModified": 1765838191,
+        "narHash": "sha256-m5KWt1nOm76ILk/JSCxBM4MfK3rYY7Wq9/TZIIeGnT8=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "00d2457e2f608b4be6fe8b470b0a36816324b0ae",
+        "rev": "c6f52ebd45e5925c188d1a20119978aa4ffd5ef6",
         "type": "github"
       },
       "original": {
         "owner": "nixos",
-        "ref": "nixos-25.05",
+        "ref": "nixos-25.11",
         "repo": "nixpkgs",
         "type": "github"
       }

utilities/nixos-installers/flake.nix

@@ -24,6 +24,7 @@
       };
 
       # Build a NixOS system that is an installation ISO with SSH enabled and bcachefs
+      # nix build .\#packages.x86_64-linux.iso-minimal-stable
       minimal =
         { nixpkgs, system }:
         nixpkgs.lib.nixosSystem {
@@ -50,6 +51,18 @@
                   # Required as a workaround for bug
                   # https://github.com/NixOS/nixpkgs/issues/32279
                   keyutils
+
+                  (pkgs.writeShellScriptBin "speedtest_fs" ''
+                    dir=''$(pwd)
+                    drive=$(df -h ''${dir} | awk 'NR==2 {print $1}')
+                    echo Testing read speeds on drive ''${drive}
+                    sudo hdparm -Tt ''${drive}
+                    test_file=''$(date +%u%m%d)
+                    test_file="''${dir}/speedtest_fs_''${test_file}"
+                    echo
+                    echo Testing write speeds into test file: ''${test_file}
+                    dd if=/dev/zero of=''${test_file} bs=8k count=10k; rm -f ''${test_file}
+                  '')
                 ];
                 boot.supportedFilesystems = [ "bcachefs" ];