diff --git a/.env b/.env
index b873b30b38..b7e7008b9b 100644
--- a/.env
+++ b/.env
@@ -9,7 +9,8 @@ PROXY=
 TOKEN=
 # Change this path to save the volume content on disk.
 CACHE=
-#build_root=
+build_root=
+BUILD_ROOT=
 
 #VOLUME="${ARCH}-ubuntu-${UBUNTU}-${HOST_COMPILER}-${COMPILER}-cache"
 #TMP="${CACHE}${VOLUME}/"
diff --git a/docker-compose.yml b/docker-compose.yml
index 9f774957a9..e5ee0df5e0 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -69,6 +69,10 @@ version: '3.8'
 volumes:
   ubuntu-cpp:
     name: "${ARCH}-ubuntu-${UBUNTU}-${HOST_COMPILER}-${COMPILER}-cache"
+  ubuntu-cpp-test:
+    name: "${ARCH}-ubuntu-${UBUNTU}-${HOST_COMPILER}-${COMPILER}-cache-test"
+  ubuntu-cpp-test2:
+    name: "${ARCH}-ubuntu-${UBUNTU}-${HOST_COMPILER}-${COMPILER}-cache-test2"
   alpine-cpp:
     name: "${ARCH}-alpine-${HOST_COMPILER}-${COMPILER}-cache"
 
@@ -147,6 +151,8 @@ services:
     volumes: &ubuntu-volumes
       - .:/vt:delegated
       - ${CACHE}ubuntu-cpp:/build:delegated
+      - ${build_root}ubuntu-cpp-test:/build2:delegated
+      - ${BUILD_ROOT}ubuntu-cpp-test2:/build22:delegated
     command: &vt-cpp-command >
       /bin/bash -c "
         /vt/ci/build_cpp.sh /vt /build &&