diff --git a/bin/chef/clean_clients.sh b/bin/chef/clean_clients.sh
new file mode 100755
index 00000000..7a26beaf
--- /dev/null
+++ b/bin/chef/clean_clients.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+echo "clean chef clients"
+yes | knife client bulk delete '^(?!chef-).*'
+if [[ "$?" != "0" ]]; then
+    echo "failed to clean all clients"
+fi
diff --git a/bin/chef/clean_environments.sh b/bin/chef/clean_environments.sh
new file mode 100755
index 00000000..f9b5052f
--- /dev/null
+++ b/bin/chef/clean_environments.sh
@@ -0,0 +1,13 @@
+#!/bin/bash
+echo "clean chef environments"
+environments=$(knife environment list)
+for environment in $environments; do
+    if [[ "$environment" != "_default" ]]; then
+        yes | knife environment delete $environment
+	if [[ "$?" != "0" ]]; then
+	    echo "failed to delete environment $environment"
+	else
+	    echo "environment $environment is deleted"
+	fi
+    fi
+done
diff --git a/bin/chef/clean_nodes.sh b/bin/chef/clean_nodes.sh
new file mode 100755
index 00000000..8224b82d
--- /dev/null
+++ b/bin/chef/clean_nodes.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+echo "clean chef nodes"
+yes | knife node bulk delete '.*'
+if [[ "$?" != "0" ]]; then
+    echo "failed to clean all nodes"
+fi
diff --git a/bin/clean_installation_logs.py b/bin/clean_installation_logs.py
new file mode 100755
index 00000000..c15c8707
--- /dev/null
+++ b/bin/clean_installation_logs.py
@@ -0,0 +1,50 @@
+#!/usr/bin/env python
+#
+# Copyright 2014 Huawei Technologies Co. Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""clean all installation logs."""
+import logging
+import os
+import os.path
+import site
+import sys
+
+activate_this = '$PythonHome/bin/activate_this.py'
+execfile(activate_this, dict(__file__=activate_this))
+site.addsitedir('$PythonHome/lib/python2.6/site-packages')
+sys.path.append('$PythonHome')
+os.environ['PYTHON_EGG_CACHE'] = '/tmp/.egg'
+
+from compass.utils import flags
+from compass.utils import logsetting
+from compass.utils import setting_wrapper as setting
+
+
+def clean_installation_logs():
+    installation_log_dirs = setting.INSTALLATION_LOGDIR
+    successful = True
+    for _, logdir in installation_log_dirs.items():
+        cmd = 'rm -rf %s/*' % logdir
+        status = os.system(cmd)
+        logging.info('run cmd %s resturns %s', cmd, status)
+        if status:
+            successful = False
+    return successful
+
+
+if __name__ == "__main__":
+    flags.init()
+    logsetting.init()
+    clean_installation_logs()
diff --git a/bin/cobbler/remove_systems.sh b/bin/cobbler/remove_systems.sh
new file mode 100755
index 00000000..1973d430
--- /dev/null
+++ b/bin/cobbler/remove_systems.sh
@@ -0,0 +1,9 @@
+#!/bin/bash
+systems=$(cobbler system list)
+echo "remove systems: $systems"
+for system in $systems; do
+    cobbler system remove --name=$system
+    if [[ "$?" != "0" ]]; then
+	echo "failed to remove system %s"
+    fi
+done
diff --git a/bin/refresh.sh b/bin/refresh.sh
index 144a839b..b2c5ac84 100755
--- a/bin/refresh.sh
+++ b/bin/refresh.sh
@@ -2,9 +2,15 @@
 set -e
 service mysqld restart
 /opt/compass/bin/manage_db.py createdb
+echo "You may run '/opt/compass/bin/clean_nodes.sh' to clean nodes on chef server"
+echo "You may run '/opt/compass/bin/clean_clients.sh' to clean clients on chef server"
+echo "you may run '/opt/compass/bin/clean_environments.sh' to clean environments on chef server"
+echo "you may run '/opt/compass/bin/remove_systems.sh' to clean systems on cobbler"
+/opt/compass/bin/clean_installation_logs.py
 service httpd restart
 service rsyslog restart
 service redis restart
+sleep 10
 redis-cli flushall
 service compass-celeryd restart
 service compass-progress-updated restart
diff --git a/compass/db/api/database.py b/compass/db/api/database.py
index cea31e99..fcb98a05 100644
--- a/compass/db/api/database.py
+++ b/compass/db/api/database.py
@@ -66,7 +66,6 @@ def session():
        .. note::
        To operate database, it should be called in database session.
     """
-    import traceback
     if hasattr(SESSION_HOLDER, 'session'):
         logging.error('we are already in session')
         raise exception.DatabaseException('session already exist')
diff --git a/install/compass.sh b/install/compass.sh
index 2457e0d9..ac40e9b1 100755
--- a/install/compass.sh
+++ b/install/compass.sh
@@ -16,6 +16,7 @@ sudo cp -rf $COMPASSDIR/bin/*.sh /opt/compass/bin/
 sudo cp -rf $COMPASSDIR/bin/compassd /usr/bin/
 sudo cp -rf $COMPASSDIR/bin/compass /usr/bin/
 sudo cp -rf $COMPASSDIR/bin/chef/* /opt/compass/bin/
+sudo cp -rf $COMPASSDIR/bin/cobbler/* /opt/compass/bin/
 sudo cp -rf $WEB_HOME/public/* /var/www/compass_web/
 sudo cp -rf $WEB_HOME/v2 /var/www/compass_web/
 sudo cp -rf $COMPASSDIR/templates /etc/compass/
@@ -49,15 +50,13 @@ sudo sed -i "s/\$cobbler_ip/$ipaddr/g" /etc/compass/os_installer/cobbler.conf
 sudo sed -i "/CHEF_INSTALLER_URL/c\CHEF_INSTALLER_URL = 'https:\/\/$ipaddr/'" /etc/compass/setting
 sudo sed -i "s/\$chef_ip/$ipaddr/g" /etc/compass/package_installer/chef-icehouse.conf
 sudo sed -i "s/\$chef_hostname/$HOSTNAME/g" /etc/compass/package_installer/chef-icehouse.conf
-sudo sed -i "s/\$compass_ip/$ipaddr/g" /etc/compass/global_config
-sudo sed -i "s/\$compass_hostname/$HOSTNAME/g" /etc/compass/global_config
-sudo sed -i "s/\$compass_testmode/$TESTMODE/g" /etc/compass/global_config
 sudo sed -e 's|$PythonHome|'$VIRTUAL_ENV'|' -i /var/www/compass/compass.wsgi
 sudo sed -e 's|$PythonHome|'$VIRTUAL_ENV'|' -i /usr/bin/compass
 sudo sed -e 's|$PythonHome|'$VIRTUAL_ENV'|' -i /opt/compass/bin/poll_switch.py
 sudo sed -e 's|$PythonHome|'$VIRTUAL_ENV'|' -i /opt/compass/bin/progress_update.py
 sudo sed -e 's|$PythonHome|'$VIRTUAL_ENV'|' -i /opt/compass/bin/manage_db.py
 sudo sed -e 's|$PythonHome|'$VIRTUAL_ENV'|' -i /opt/compass/bin/client.py
+sudo sed -e 's|$PythonHome|'$VIRTUAL_ENV'|' -i /opt/compass/bin/clean_installation_logs.py
 sudo sed -e 's|$Python|'$VIRTUAL_ENV/bin/python'|' -i /etc/init.d/compass-progress-updated
 sudo sed -e 's|$CeleryPath|'$VIRTUAL_ENV/bin/celery'|' -i /etc/init.d/compass-celeryd
 sudo sed -i "s/\$ipaddr/$ipaddr/g" /etc/compass/os_metadata/general.conf