DOCS-1351 - updated keepalive info

Author: Michael Paik

source/faq/diagnostics.txt

@@ -29,31 +29,47 @@ following commands:
 
 .. _faq-keepalive:
 
-Does TCP ``keepalive`` time affect sharded clusters and replica sets?
----------------------------------------------------------------------
-
-If you experience socket errors between members of a sharded cluster
-or replica set, that do not have other reasonable causes, check the
-TCP keep alive value, which Linux systems store as the
-``tcp_keepalive_time`` value. A common keep alive period is ``7200``
-seconds (2 hours); however, different distributions and OS X may have
-different settings. For MongoDB, you will have better experiences with
-shorter keepalive periods, on the order of ``120`` seconds (two minutes).
+Does TCP ``keepalive`` time affect MongoDB Deployments?
+-------------------------------------------------------
+
+If you experience socket errors between clients and servers or between
+members of a sharded cluster or replica set that do not have other
+reasonable causes, check the TCP keepalive value, which Linux systems
+store as the ``tcp_keepalive_time`` value. A common keepalive period
+is ``7200`` seconds (2 hours); however, different distributions and OS
+X may have different settings. For MongoDB, you will have better
+experiences with shorter keepalive periods, on the order of ``120``
+seconds (two minutes).
+
+If your MongoDB deployment experiences keepalive-related issues, you
+must alter the ``tcp_keepalive_time`` value on all machines hosting
+MongoDB processes. This includes all machines hosting
+:program:`mongos` or :program:`mongod` servers and all machines
+hosting client processes that connect to MongoDB.
+
+.. versionchanged:: 2.0
+
+Beginning in release series 2.0, :program:`mongod` and :program:`mongos`
+processes independently set keepalive times to a minumum of 5 minutes on
+their own sockets.
 
 .. include:: /includes/fact-tcp-keepalive-linux.rst
 .. include:: /includes/fact-tcp-keepalive-osx.rst
+
+The above methods of setting the TCP keepalive are not persistent; you
+will need to reset the new ``tcp_keepalive_time`` value each time you
+reboot or restart a system. see your operating system's documentation
+for setting the TCP keepalive value persistently.
+
 .. include:: /includes/fact-tcp-keepalive-windows.rst
 
-The new ``tcp_keepalive_time`` value takes effect without requiring
-you to restart the :program:`mongod` or :program:`mongos`
-servers. When you reboot or restart your system you will need to set
-the new ``tcp_keepalive_time`` value, or see your operating system's
-documentation for setting the TCP keepalive value persistently.
+.. versionchanged:: 2.0
 
-If your replica set or sharded cluster experiences keepalive-related
-issues, you must alter the ``tcp_keepalive_time`` value on all machines
-hosting MongoDB processes. This includes all machines hosting
-:program:`mongos` or :program:`mongod` servers.
+You will need to restart :program:`mongod` and :program:`mongos`
+servers for new system-wide ``tcp_keepalive_time`` settings to take
+effect on server versions newer than 2.0 if the new value is less than
+600 seconds.  Values greater than or equal to 600 seconds will be
+ignored by :program:`mongod` and :program:`mongos`.
 
 What tools are available for monitoring MongoDB?
 ------------------------------------------------