DOCSP-13929 Rewrites Number of mongos and Distribution on Sharded Cluster Components (#2879)

* Rewrites Number of mongos and Distribution on Sharded Cluster Components

* internal review feedback

Author: jmd-mongo

source/core/sharded-cluster-components.txt

@@ -65,22 +65,21 @@ the  near future, but do not need to at the time of deployment.
 Number of ``mongos`` and Distribution
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Deploying multiple :binary:`~bin.mongos` routers supports high
-availability and scalability. If a proxy or load balancer is between the 
-application and the ``mongos`` routers, you must configure it for 
-:term:`client affinity`. Client affinity allows every connection from a 
-single client to reach the same ``mongos``. For shard-level high 
-availability, a common pattern is to place ``mongos`` instances on the 
-same hardware that ``mongos`` instances are already running on.
-Another option is to embed ``mongos`` routers with
-application tier infrastructure.
-
-There is no limit to the number of :binary:`~bin.mongos` routers you can
-have in a deployment. However, as :binary:`~bin.mongos` routers
-communicate frequently with your config servers, monitor config server
-performance closely as you increase the number of routers. If you see
-performance degradation, it may be beneficial to cap the number of
-:binary:`~bin.mongos` routers in your deployment.
+:binary:`~bin.mongos` routers support high availability and scalability
+when deploying multiple ``mongos`` instances. If a proxy or load 
+balancer is between the application and the ``mongos`` routers, you 
+must configure it for :term:`client affinity`. Client affinity allows 
+every connection from a single client to reach the same ``mongos``. 
+For shard-level high availability, either:
+
+- Add ``mongos`` instances on the same hardware where ``mongos`` 
+  instances are already running.
+- Embed ``mongos`` routers at the application level.
+
+:binary:`~bin.mongos` routers communicate frequently with your config 
+servers. As you increase the number of routers, performance may degrade. 
+If performance degrades, reduce the number of routers. Your deployment 
+should not have more than 30 ``mongos`` routers.
 
 The following diagram shows a common sharded cluster architecture used
 in production: