diff --git a/releasenotes/notes/random-bytes-size-limit-ee94a8c6534fe916.yaml b/releasenotes/notes/random-bytes-size-limit-ee94a8c6534fe916.yaml
new file mode 100644
index 0000000..42322e4
--- /dev/null
+++ b/releasenotes/notes/random-bytes-size-limit-ee94a8c6534fe916.yaml
@@ -0,0 +1,9 @@
+---
+upgrade:
+  - |
+    The ``tempest.lib.common.utils.data_utils.random_bytes()`` helper
+    function will no longer allow a ``size`` of more than 1MiB. Tests
+    generally do not need to generate and use large payloads for
+    feature verification and it is easy to lose track of and duplicate
+    large buffers. The sum total of such errors can become problematic
+    in paralllelized and constrained CI environments.
diff --git a/tempest/lib/common/utils/data_utils.py b/tempest/lib/common/utils/data_utils.py
index 44b55eb..b6671b5 100644
--- a/tempest/lib/common/utils/data_utils.py
+++ b/tempest/lib/common/utils/data_utils.py
@@ -169,6 +169,8 @@
     :return: size randomly bytes
     :rtype: string
     """
+    if size > 1 << 20:
+        raise RuntimeError('Size should be less than 1MiB')
     return b''.join([six.int2byte(random.randint(0, 255))
                      for i in range(size)])