diff --git a/tempest/services/volume/v2/json/volumes_client.py b/tempest/services/volume/v2/json/volumes_client.py
index 5bfa75f..df20a2a 100644
--- a/tempest/services/volume/v2/json/volumes_client.py
+++ b/tempest/services/volume/v2/json/volumes_client.py
@@ -68,10 +68,10 @@
         body = json.loads(body)
         return resp, body['volume']
 
-    def create_volume(self, size, **kwargs):
+    def create_volume(self, size=None, **kwargs):
         """
         Creates a new Volume.
-        size(Required): Size of volume in GB.
+        size: Size of volume in GB.
         Following optional keyword arguments are accepted:
         name: Optional Volume Name.
         metadata: A dictionary of values to be used as metadata.
@@ -79,6 +79,10 @@
         snapshot_id: When specified the volume is created from this snapshot
         imageRef: When specified the volume is created from this image
         """
+        # for bug #1293885:
+        # If no size specified, read volume size from CONF
+        if size is None:
+            size = CONF.volume.volume_size
         post_body = {'size': size}
         post_body.update(kwargs)
         post_body = json.dumps({'volume': post_body})
diff --git a/tempest/services/volume/v2/xml/volumes_client.py b/tempest/services/volume/v2/xml/volumes_client.py
index e735a65..1fdaf19 100644
--- a/tempest/services/volume/v2/xml/volumes_client.py
+++ b/tempest/services/volume/v2/xml/volumes_client.py
@@ -117,10 +117,10 @@
         body = self._check_if_bootable(body)
         return resp, body
 
-    def create_volume(self, size, **kwargs):
+    def create_volume(self, size=None, **kwargs):
         """Creates a new Volume.
 
-        :param size: Size of volume in GB. (Required)
+        :param size: Size of volume in GB.
         :param name: Optional Volume Name.
         :param metadata: An optional dictionary of values for metadata.
         :param volume_type: Optional Name of volume_type for the volume
@@ -129,6 +129,10 @@
         :param imageRef: When specified the volume is created from this
                          image
         """
+        # for bug #1293885:
+        # If no size specified, read volume size from CONF
+        if size is None:
+            size = CONF.volume.volume_size
         # NOTE(afazekas): it should use a volume namespace
         volume = common.Element("volume", xmlns=common.XMLNS_11, size=size)