diff --git a/lib/tempest b/lib/tempest
index cc65ec7..537da61 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -430,6 +430,12 @@
         TEMPEST_VOLUME_MANAGE_VOLUME=${TEMPEST_VOLUME_MANAGE_VOLUME:-True}
     fi
     iniset $TEMPEST_CONFIG volume-feature-enabled manage_volume $(trueorfalse False TEMPEST_VOLUME_MANAGE_VOLUME)
+    # Only turn on TEMPEST_EXTEND_ATTACHED_VOLUME by default for "lvm" backends
+    # in Cinder and the libvirt driver in Nova.
+    if [[ "$CINDER_ENABLED_BACKENDS" == *"lvm"* ]] && [ "$VIRT_DRIVER" = "libvirt" ]; then
+        TEMPEST_EXTEND_ATTACHED_VOLUME=${TEMPEST_EXTEND_ATTACHED_VOLUME:-True}
+    fi
+    iniset $TEMPEST_CONFIG volume-feature-enabled extend_attached_volume $(trueorfalse False TEMPEST_EXTEND_ATTACHED_VOLUME)
     # TODO(ameade): Remove the api_v3 flag when Mitaka and Liberty are end of life.
     iniset $TEMPEST_CONFIG volume-feature-enabled api_v3 True
     iniset $TEMPEST_CONFIG volume-feature-enabled api_v1 $(trueorfalse False TEMPEST_VOLUME_API_V1)