release notes scafolding

Author: Sam Kleinman

source/release-notes/2.2.txt

@@ -10,11 +10,33 @@ Release Notes for MongoDB Version 2.2
 
 Upgrading
 ---------
-
-.. TODO crib from 2.0, with caveat about mongos' before mongod with
-   auth.
 
-also drivers need to upgrade to -next if using authentication.
+Upgrade drivers if using authentication, before upgrading mongod
+
+Although the major version number has changed, MongoDB 2.0 is a standard, 
+incremental production release and works as a drop-in replacement for MongoDB 
+1.8. However, there are a few changes you must be aware of before attempting to 
+upgrade:
+
+2.0 processes can talk to 1.8 processes and vice versa, so you can upgrade 
+various parts of a cluster in any order.
+
+To upgrade a standalone server. Shutdown the old mongod and then restart with 
+the new mongod binary. You can download the v2.0 binaries from the MongoDB 
+Download Page.
+
+To upgrade a replica set, in the most efficent way possible, while minimizing 
+the amount of downtime, use the following procedure. Upgrade the secondaries 
+first one at a time, then s tepDown the primary and upgrade the primary. Using 
+the stepDown command is better than simply shutting it down since the failover 
+will happen quicker. To avoid losing the last few updates on failover you can 
+temporarily halt your application (failover should take less than 10 seconds) 
+or change your application code to confirm that each update reaches multiple 
+servers. Note, after upgrading to 2.0 you can use the shutdown command to 
+shutdown the primary without losing any safe updates.
+
+To upgrade a shard cluster, if using authentication, you *must* upgrade the 
+``mongos`` first and then upgrade ``mongod``.
 
 Changes
 -------