DOCSP-48525-disaster-recovery-faq-entry

source/about-mongosync.txt

@@ -19,6 +19,10 @@ destination cluster and keeps the clusters in continuous sync until you
 In addition to continuous data synchronization, ``mongosync`` can also
 perform a one time data migration between clusters.
 
+.. important::
+
+   .. include:: /includes/fact-no-mongosync-disaster-recovery.rst
+
 ``mongosync`` keeps track of its current actions through 
 :ref:`states <c2c-states>`. ``mongosync`` enters different states depending on 
 the requests it receives. The current ``mongosync`` state determines which API 

source/faq.txt

@@ -23,6 +23,8 @@ Can I change the load level while ``mongosync`` is syncing?
 Yes, you can adjust the cluster workload level during a migration by 
 following the steps in :ref:`c2c-reconfigure-mid-migration`. 
 
+.. _c2c-faq-reads-writes-mongosync:
+
 Can I perform reads or writes to my destination cluster while ``mongosync`` is syncing?
 ---------------------------------------------------------------------------------------
 
@@ -232,4 +234,11 @@ Can I customize chunk distributions when syncing into a sharded cluster?
 No, you can't configure ``mongosync`` to customize chunk distributions
 on a destination sharded cluster.  ``mongosync`` samples each collection
 during initialization to determine how to distribute documents
-efficiently across the destination cluster’s shards after migration.
+efficiently across the destination cluster’s shards after migration.
+
+Can I use ``mongosync`` to set up a Disaster Recovery cluster?
+--------------------------------------------------------------
+
+No, you can't currently set up a Disaster Recovery cluster with ``mongosync``, 
+since ``mongosync`` **must commit** in order to safely accept traffic to the 
+destination cluster. For more information, see :ref:`c2c-faq-reads-writes-mongosync`.

source/includes/fact-no-mongosync-disaster-recovery.rst

@@ -0,0 +1,4 @@
+Until you've called commit on ``mongosync`` and ``canWrite`` successfully 
+returns ``true``, the destination cluster cannot be used to accept 
+application read or write traffic. 
+Do not use ``mongosync`` for maintaining Disaster Recovery clusters.

source/index.txt

@@ -13,6 +13,10 @@ enable {+c2c-product-name+} with the :ref:`mongosync <c2c-mongosync>` utility.
 
 For an overview of the ``mongosync`` process, see :ref:`about-mongosync`.
 
+.. important::
+
+   .. include:: /includes/fact-no-mongosync-disaster-recovery.rst
+
 To get started with ``mongosync``, refer to the :ref:`Quick Start Guide
 <c2c-quickstart>`. For more detailed information, refer to the
 :ref:`c2c-install` or :ref:`c2c-connecting` page that best fits your

source/quickstart.txt

@@ -41,6 +41,10 @@ the rest of the {+c2c-product-name+} documentation.
   ``mongosync`` syncs writes on the source cluster for the 
   duration of the migration until commit is called.
 
+.. important::
+
+   .. include:: /includes/fact-no-mongosync-disaster-recovery.rst
+
 Follow the instructions below to set up {+c2c-product-name+}, connect
 your clusters, and synchronize your data.
 

source/reference/mongosync/mongosync-behavior.txt

@@ -219,6 +219,10 @@ For any continuous synchronization use cases with ``mongosync``, ensure that
 ``mongosync`` commits before cutting over from the source to the 
 destination.
 
+.. important::
+
+   .. include:: /includes/fact-no-mongosync-disaster-recovery.rst
+
 If the source cluster shuts down before ``mongosync`` can commit, such as in 
 a disaster scenario, the destination cluster might not have a consistent 
 snapshot of the source data. To learn more, see :ref:`c2c-behavior-consistency`.