diff --git a/doc/source/configuration.rst b/doc/source/configuration.rst
index 064bf515e6..3e0d09f96a 100644
--- a/doc/source/configuration.rst
+++ b/doc/source/configuration.rst
@@ -667,7 +667,7 @@ with ``VOLUME_BACKING_FILE_SIZE``.
 
         VOLUME_GROUP_NAME="stack-volumes"
         VOLUME_NAME_PREFIX="volume-"
-        VOLUME_BACKING_FILE_SIZE=10250M
+        VOLUME_BACKING_FILE_SIZE=24G
 
 
 Keystone
diff --git a/stackrc b/stackrc
index 31c2d695ac..cf81e51ebf 100644
--- a/stackrc
+++ b/stackrc
@@ -742,8 +742,8 @@ for image_url in ${IMAGE_URLS//,/ }; do
     fi
 done
 
-# 10Gb default volume backing file size
-VOLUME_BACKING_FILE_SIZE=${VOLUME_BACKING_FILE_SIZE:-10250M}
+# 24Gb default volume backing file size
+VOLUME_BACKING_FILE_SIZE=${VOLUME_BACKING_FILE_SIZE:-24G}
 
 # Prefixes for volume and instance names
 VOLUME_NAME_PREFIX=${VOLUME_NAME_PREFIX:-volume-}