upgrade guide

docs/source/index.rst

@@ -53,6 +53,7 @@ Contents:
    plugins
    tune
    changes
+   upgrade
 
 -------
 License

docs/source/upgrade.rst

@@ -0,0 +1,33 @@
+
+.. _upgrade:
+
+=============
+Upgrade Guide
+=============
+
+.. _upgrade_1.1.2:
+
+----------------
+Upgrade to 1.1.2
+----------------
+
+.. NOTE:: 1.0+ releases can be upgraded to 1.1.2 smoothly
+
+Steps:
+
+1. Download and install emqttd-1.1.2 to the new directory, for example::
+
+    Old installation: /opt/emqttd_1_0_0/
+
+    New installation: /opt/emqttd_1_1_2/
+
+2. Copy the 'etc/' and 'data/' from the old installation::
+
+    cp -R /opt/emqttd_1_0_0/etc/* /opt/emqttd_1_1_2/etc/
+
+    cp -R /opt/emqttd_1_0_0/data/* /opt/emqttd_1_1_2/data/
+
+3. Copy the plugins/{plugin}/etc/* from the old installation if you loaded plugins.
+
+4. Stop the old emqttd, and start the new one.
+