diff --git a/.github/scripts/oswal-s3-bench-run.sh b/.github/scripts/oswal-s3-bench-run.sh
index 2011322d278..a9835c1e5f1 100644
--- a/.github/scripts/oswal-s3-bench-run.sh
+++ b/.github/scripts/oswal-s3-bench-run.sh
@@ -31,6 +31,7 @@ pull_images() {
 }
 
 wal_disk() {
+    : "${RESULTS:?}"
     local root=$1 device
     device=$(lsblk -dnpo NAME,MODEL | awk '/Instance Storage/ {print $1; exit}')
     # Only a smoke run may keep the Raft Engine WAL on the root volume.
@@ -42,7 +43,7 @@ wal_disk() {
         sudo -n mount -o noatime "$device" "$root"
     fi
     sudo -n chown "$(id -u):$(id -g)" "$root"
-    findmnt -no SOURCE,FSTYPE -T "$root"
+    findmnt -no SOURCE,FSTYPE -T "$root" | tee "$RESULTS/wal-disk.txt"
 }
 
 generate() {
diff --git a/.github/workflows/oswal-s3-bench.yml b/.github/workflows/oswal-s3-bench.yml
index 20b680d23ce..c31dfe8f1c3 100644
--- a/.github/workflows/oswal-s3-bench.yml
+++ b/.github/workflows/oswal-s3-bench.yml
@@ -170,7 +170,7 @@ jobs:
         AWS_SECRET_ACCESS_KEY: ${{ inputs.smoke && 'superpower_password' || secrets.AWS_CI_TEST_SECRET_ACCESS_KEY }}
       run: uv run greptimedb/.github/scripts/oswal-s3-bench.py probe --bucket "$S3_BUCKET" --region "$S3_REGION" --endpoint "$S3_ENDPOINT" --prefix "$RUN_PREFIX"
     - name: Put the Raft Engine WAL on the instance store
-      run: bash greptimedb/.github/scripts/oswal-s3-bench-run.sh wal-disk "$WAL_ROOT" | tee "$RESULTS/wal-disk.txt"
+      run: bash greptimedb/.github/scripts/oswal-s3-bench-run.sh wal-disk "$WAL_ROOT"
     - name: Generate the dataset once
       run: bash greptimedb/.github/scripts/oswal-s3-bench-run.sh generate
     - name: Load every cell
diff --git a/tests/perf/test_oswal_s3_bench_scripts.py b/tests/perf/test_oswal_s3_bench_scripts.py
index 30eaf0ef20a..dc81240f1ae 100644
--- a/tests/perf/test_oswal_s3_bench_scripts.py
+++ b/tests/perf/test_oswal_s3_bench_scripts.py
@@ -268,7 +268,7 @@ class CellLifecycleTest(unittest.TestCase):  # the run script against fake docke
         with tempfile.TemporaryDirectory() as directory:
             (Path(directory) / "lsblk").write_text("#!/usr/bin/env bash\necho '/dev/nvme0n1 Amazon Elastic Block Store'\n")
             (Path(directory) / "lsblk").chmod(0o755)
-            env = os.environ | {"PATH": f"{directory}:{os.environ['PATH']}", "SMOKE": "false"}
+            env = os.environ | {"PATH": f"{directory}:{os.environ['PATH']}", "SMOKE": "false", "RESULTS": directory}
             done = subprocess.run(["bash", str(SCRIPTS / "oswal-s3-bench-run.sh"), "wal-disk", f"{directory}/wal"],
                                   env=env, capture_output=True, text=True, timeout=60)
             self.assertNotEqual(done.returncode, 0)