diff --git a/kloudbuster/force_cleanup.py b/kloudbuster/force_cleanup.py
index b92edac..80e7812 100755
--- a/kloudbuster/force_cleanup.py
+++ b/kloudbuster/force_cleanup.py
@@ -168,6 +168,8 @@ class StorageCleaner(AbstractCleaner):
                         except NotFound:
                             print 'WARNING: Volume %s attached to an instance that no longer '\
                                   'exists (will require manual cleanup of the database)' % (id)
+                        except Exception as e:
+                            print str(e)
                     else:
                         # no attachments
                         kb_volumes.append(vol)
diff --git a/kloudbuster/kb_config.py b/kloudbuster/kb_config.py
index 02041ae..f8858bf 100644
--- a/kloudbuster/kb_config.py
+++ b/kloudbuster/kb_config.py
@@ -145,6 +145,15 @@ class KBConfig(object):
         self.config_scale['server'] = self.server_cfg
         self.config_scale['client'] = self.client_cfg
 
+        # missing rate or rate_iops = 0 = no-limit
+        # note we need to use key based access to modify the content
+        # (self.config_scale['client'].storage_tool_configs will make a shallow copy)
+        for tc in self.config_scale['client']['storage_tool_configs']:
+            if 'rate' not in tc:
+                tc['rate'] = '0'
+            if 'rate_iops' not in tc:
+                tc['rate_iops'] = 0
+
     def init_with_cli(self):
         self.storage_mode = CONF.storage
         self.multicast_mode = CONF.multicast
diff --git a/kloudbuster/kb_runner_storage.py b/kloudbuster/kb_runner_storage.py
index 7c01dce..c3738a2 100644
--- a/kloudbuster/kb_runner_storage.py
+++ b/kloudbuster/kb_runner_storage.py
@@ -71,8 +71,8 @@ class KBRunner_Storage(KBRunner):
         return msg
 
     def init_volume(self, active_range):
-        # timeout is calculated as 30s/GB
-        timeout = 30 * self.config.storage_stage_configs.io_file_size
+        # timeout is calculated as 30s/GB/client VM
+        timeout = 30 * self.config.storage_stage_configs.io_file_size * len(self.client_dict)
         parameter = {'size': str(self.config.storage_stage_configs.io_file_size) + 'GiB'}
         parameter['mkfs'] = True \
             if self.config.storage_stage_configs.target == 'volume' else False
@@ -205,14 +205,18 @@ class KBRunner_Storage(KBRunner):
                             cur_iops = int(self.tool_result[idx]['write_iops'])
                             cur_rate = int(self.tool_result[idx]['write_bw'])
 
-                        degrade_iops = (req_iops - cur_iops) * 100 / req_iops if req_iops else 0
-                        degrade_rate = (req_rate - cur_rate) * 100 / req_rate if req_rate else 0
-                        if ((cur_tc['mode'] in ['randread', 'randwrite'] and degrade_iops > limit)
-                           or (cur_tc['mode'] in ['read', 'write'] and degrade_rate > limit)):
-                            LOG.warning('KloudBuster is stopping the iteration because the result '
-                                        'reaches the stop limit.')
-                            tc_flag = False
-                            break
+                        # some runs define an unlimited iops/bw in this case
+                        # we never abort the iteration
+                        if req_iops or req_rate:
+                            degrade_iops = (req_iops - cur_iops) * 100 / req_iops if req_iops else 0
+                            degrade_rate = (req_rate - cur_rate) * 100 / req_rate if req_rate else 0
+                            if ((cur_tc['mode'] in ['randread', 'randwrite'] and
+                                degrade_iops > limit)
+                               or (cur_tc['mode'] in ['read', 'write'] and degrade_rate > limit)):
+                                LOG.warning('KloudBuster is stopping the iteration '
+                                            'because the result reaches the stop limit.')
+                                tc_flag = False
+                                break
                 if timeout_vms:
                     LOG.warning('KloudBuster is stopping the iteration because of there are %d '
                                 'VMs timing out' % timeout_vms)