(DOCSP-27444): Increased open files for incoming connections in 4.2 (#2438)

* WIP

* (DOCSP-27444): Increased open files for incoming connections in 4.2

* ordering

* wording

* format replacements

* wording

* reorder phrases

* wording

* change language and add incldue to upgrade procedures

* staging fix

* add missing replacements

Author: jeff-allen-mongo

source/includes/4.2-changes/open-file-connection-increase.rst

@@ -0,0 +1,7 @@
+Starting in MongoDB 4.2, incoming connections to a :binary:`mongod` or
+:binary:`mongos` instance require **two** file descriptors. In previous
+versions of MongoDB, incoming connections required **one** file
+descriptor.
+
+Prior to upgrading from MongoDB 4.0 to 4.2, you may need to increase the
+value of your open files |ulimit| setting (``-n``).

source/reference/ulimit.txt

@@ -30,7 +30,7 @@ deployment and its use to determine ideal ``ulimit`` settings.
 
 Generally, all :binary:`~bin.mongod` and :binary:`~bin.mongos` instances:
 
-- track each incoming connection with a file descriptor *and* a
+- track each incoming connection with two file descriptors *and* a
   thread.
 
 - track each internal thread or *pthread* as a system process.
@@ -205,6 +205,16 @@ Always remember to restart your :binary:`~bin.mongod` and
 :binary:`~bin.mongos` instances after changing the ``ulimit`` settings to
 ensure that the changes take effect.
 
+Considerations
+``````````````
+
+.. |ulimit| replace:: ``ulimit``
+
+- .. include:: /includes/4.2-changes/open-file-connection-increase.rst
+
+- For the macOS platform, the recommended process limit is ``2500``,
+  which is the maximum configurable value for this platform.
+
 Linux distributions using Upstart
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

source/release-notes/4.2-compatibility.txt

@@ -390,6 +390,12 @@ Resume Token Modification
 
 .. include:: /includes/extracts/4.2-changes-change-stream-modification-error.rst
 
+Increased File Descriptors Required for Incoming Connections
+------------------------------------------------------------
+
+.. |ulimit| replace:: :ref:`ulimit <ulimit>`
+
+.. include:: /includes/4.2-changes/open-file-connection-increase.rst
 
 MongoDB Tools
 -------------

source/release-notes/4.2-upgrade-replica-set.txt

@@ -16,10 +16,6 @@ Upgrade a Replica Set to 4.2
 
 .. include:: /includes/upgrade-copy.rst
 
-.. note:: Starting in MongoDB 4.2
-
-   .. include:: /includes/collMod-note.rst
-
 .. |downgrading| replace:: :doc:`downgrading </release-notes/4.2-downgrade-replica-set>`
 
 Read Concern Majority (3-Member Primary-Secondary-Arbiter Architecture)
@@ -84,6 +80,13 @@ If your 4.0 deployment uses MMAPv1, you must change the 4.0 deployment
 to :doc:`/core/wiredtiger` before upgrading to MongoDB 4.2. For details,
 see :doc:`/tutorial/change-replica-set-wiredtiger`.
 
+Increase Open Files ``ulimit`` Setting
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. |ulimit| replace:: :ref:`ulimit <ulimit>`
+
+.. include:: /includes/4.2-changes/open-file-connection-increase.rst
+
 Review Current Configuration
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

source/release-notes/4.2-upgrade-sharded-cluster.txt

@@ -78,6 +78,13 @@ If your 4.0 deployment uses MMAPv1, you must change the 4.0 deployment
 to :doc:`/core/wiredtiger` before upgrading to MongoDB 4.2. For details,
 see :doc:`/tutorial/change-sharded-cluster-wiredtiger`.
 
+Increase Open Files ``ulimit`` Setting
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. |ulimit| replace:: :ref:`ulimit <ulimit>`
+
+.. include:: /includes/4.2-changes/open-file-connection-increase.rst
+
 Review Current Configuration
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

source/release-notes/4.2-upgrade-standalone.txt

@@ -34,6 +34,13 @@ If your 4.0 deployment uses MMAPv1, you must change the 4.0 deployment
 to :doc:`/core/wiredtiger` before upgrading to MongoDB 4.2. For details,
 see :doc:`/tutorial/change-standalone-wiredtiger`.
 
+Increase Open Files ``ulimit`` Setting
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. |ulimit| replace:: :ref:`ulimit <ulimit>`
+
+.. include:: /includes/4.2-changes/open-file-connection-increase.rst
+
 Review Current Configuration
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~