Note to help diagnose errors with docker's default location for building
images.
diff --git a/tools/run_tests/README.md b/tools/run_tests/README.md
index dd727f4..e709ddd 100644
--- a/tools/run_tests/README.md
+++ b/tools/run_tests/README.md
@@ -22,6 +22,10 @@
######Example
`tools/run_tests/run_interop_tests.py -l csharp -s c++ --use_docker` (run interop tests with C# client and C++ server)
+Note: if you see an error like `no space left on device` when running the
+interop tests using Docker, make sure that Docker is building the image files in
+a location with sufficient disk space.
+
#Performance benchmarks (run_performance_tests.py)
Runs predefined benchmark scenarios for given languages. Besides the simple configuration of running all the scenarios locally,