diff --git a/Containerfile b/Containerfile
index 864e8f49..44bb9324 100644
--- a/Containerfile
+++ b/Containerfile
@@ -31,7 +31,7 @@ COPY pyproject.toml /_lock/
 # This layer is cached until uv.lock or pyproject.toml change.
 # Delete any unwanted parts of the installed packages to reduce size
 RUN --mount=type=cache,target=/root/.cache \
-    apt-get update && apt-get install build-essential -y && \
+    apt-get update && apt-get install gcc -y && \
     echo "Creating virtualenv at /venv" && \
     conda create -qy -p /venv python=3.12 numcodecs
 RUN which gcc
@@ -49,6 +49,7 @@ RUN echo "Installing dependencies into /venv" && \
 COPY . /src
 RUN --mount=type=cache,target=/root/.cache \
     uv pip install --no-deps --python=$UV_PROJECT_ENVIRONMENT /src
+RUN uv pip install dllist && python 
 
 # Copy the virtualenv into a distroless image
 # * These are small images that only contain the runtime dependencies
diff --git a/src/nwp_consumer/__init__.py b/src/nwp_consumer/__init__.py
index 4aaa887d..2cba477d 100644
--- a/src/nwp_consumer/__init__.py
+++ b/src/nwp_consumer/__init__.py
@@ -23,6 +23,8 @@
 +-------------------------------+-------------------------------------+---------------------------------------------+
 | MODEL_REPOSITORY              | The model repository to use.        | ceda-metoffice-global                       |
 +-------------------------------+-------------------------------------+---------------------------------------------+
+| CONCURRENCY                   | Whether to use concurrency.         | True                                        |
++-------------------------------+-------------------------------------+---------------------------------------------+
 
 
 Development Documentation
diff --git a/src/nwp_consumer/internal/repositories/model_repositories/ecmwf_realtime.py b/src/nwp_consumer/internal/repositories/model_repositories/ecmwf_realtime.py
index 24f5995a..0e439ca7 100644
--- a/src/nwp_consumer/internal/repositories/model_repositories/ecmwf_realtime.py
+++ b/src/nwp_consumer/internal/repositories/model_repositories/ecmwf_realtime.py
@@ -198,7 +198,7 @@ def _download(self, url: str) -> ResultE[pathlib.Path]:
         ).with_suffix(".grib").expanduser()
 
         # Only download the file if not already present
-        if not local_path.exists():
+        if not local_path.exists() or local_path.stat().st_size == 0:
             local_path.parent.mkdir(parents=True, exist_ok=True)
             log.debug("Requesting file from S3 at: '%s'", url)
 
diff --git a/src/nwp_consumer/internal/repositories/model_repositories/test_noaa_gfs.py b/src/nwp_consumer/internal/repositories/model_repositories/test_noaa_gfs.py
index 00a7494e..bd4e6b0d 100644
--- a/src/nwp_consumer/internal/repositories/model_repositories/test_noaa_gfs.py
+++ b/src/nwp_consumer/internal/repositories/model_repositories/test_noaa_gfs.py
@@ -108,3 +108,4 @@ class TestCase:
                     max_step=max(NOAAGFSS3ModelRepository.model().expected_coordinates.step),
                 )
                 self.assertEqual(result, t.expected)
+
diff --git a/src/nwp_consumer/internal/services/archiver_service.py b/src/nwp_consumer/internal/services/archiver_service.py
index 1cbe3d7a..6fb37cae 100644
--- a/src/nwp_consumer/internal/services/archiver_service.py
+++ b/src/nwp_consumer/internal/services/archiver_service.py
@@ -2,10 +2,11 @@
 
 import dataclasses
 import logging
+import os
 import pathlib
 from typing import TYPE_CHECKING, override
 
-from joblib import Parallel
+from joblib import Parallel, cpu_count
 from returns.result import Failure, ResultE, Success
 
 from nwp_consumer.internal import entities, ports
@@ -86,8 +87,12 @@ def archive(self, year: int, month: int) -> ResultE[pathlib.Path]:
                     amr = amr_result.unwrap()
 
                     # Create a generator to fetch and process raw data
+                    n_jobs: int = max(cpu_count() - 1, self.mr.repository().max_connections)
+                    if os.getenv("CONCURRENCY", "True").capitalize() == "False":
+                        n_jobs = 1
+                    log.debug(f"Downloading using {n_jobs} concurrent thread(s)")
                     da_result_generator = Parallel(
-                        n_jobs=self.mr.repository().max_connections - 1,
+                        n_jobs=n_jobs,
                         prefer="threads",
                         return_as="generator_unordered",
                     )(amr.fetch_init_data(it=it))
diff --git a/src/nwp_consumer/internal/services/consumer_service.py b/src/nwp_consumer/internal/services/consumer_service.py
index 4ac41390..d72179df 100644
--- a/src/nwp_consumer/internal/services/consumer_service.py
+++ b/src/nwp_consumer/internal/services/consumer_service.py
@@ -3,6 +3,7 @@
 import dataclasses
 import datetime as dt
 import logging
+import os
 import pathlib
 from typing import override
 
@@ -72,9 +73,13 @@ def consume(self, it: dt.datetime | None = None) -> ResultE[pathlib.Path]:
                     ))
                 amr = amr_result.unwrap()
 
+                n_jobs: int = max(cpu_count() - 1, self.mr.repository().max_connections)
+                if os.getenv("CONCURRENCY", "True").capitalize() == "False":
+                    n_jobs = 1
+                log.debug(f"Downloading using {n_jobs} concurrent thread(s)")
                 fetch_result_generator = Parallel(
                     # TODO - fix segfault when using multiple threads
-                    n_jobs=max(cpu_count() - 1, self.mr.repository().max_connections),
+                    n_jobs=n_jobs,
                     prefer="threads",
                     return_as="generator_unordered",
                 )(amr.fetch_init_data(it=it))