diff --git a/nixbld-etc-nixos/configuration.nix b/nixbld-etc-nixos/configuration.nix
index 4183876..8a8a347 100644
--- a/nixbld-etc-nixos/configuration.nix
+++ b/nixbld-etc-nixos/configuration.nix
@@ -129,13 +129,13 @@ ACTION=="add", SUBSYSTEM=="tty", \
     useSubstitutes = true;
     hydraURL = "https://nixbld.m-labs.hk";
     notificationSender = "hydra@m-labs.hk";
-    minimumDiskFree = 2;  # in GB
+    minimumDiskFree = 10;  # in GB
     minimumDiskFreeEvaluator = 1;
     buildMachinesFiles = [];
     extraConfig =
       ''
       binary_cache_secret_key_file = /etc/nixos/secret/nixbld.m-labs.hk-1
-      max_output_size = 4294967296
+      max_output_size = 5500000000
       <runcommand>
       job = artiq:main:extended-tests
       command = nix-shell `jq -r .drvPath $HYDRA_JSON` --run "python `jq -r .outputs[0].path $HYDRA_JSON` $HYDRA_JSON"