DOCSP-25925-migrationConcurrency (#2144)

* DOCSP-25925-migrationConcurrency

* DOCSP-25925-migrationConcurrency

* DOCSP-25925-migrationConcurrency

* DOCSP-25925-migrationConcurrency

* DOCSP-25925-migrationConcurrency

* DOCSP-25925-migrationConcurrency

* DOCSP-25925-migrationConcurrency

* DOCSP-25925-migrationConcurrency

* DOCSP-25925-migrationConcurrency

* DOCSP-25925-migrationConcurrency

* DOCSP-25925-migrationConcurrency

Co-authored-by: jason-price-mongodb <[email protected]>

Author: jason-price-mongodb

source/reference/parameters.txt

@@ -3064,6 +3064,40 @@ Sharding Parameters
 
       db.adminCommand( { setParameter: 1, chunkDefragmentationThrottlingMS: 10 } )
 
+.. parameter:: chunkMigrationConcurrency
+
+   .. versionadded:: 6.3
+
+   *Type*: integer
+
+   *Default*: 1
+
+   |both|
+
+   Specifies an integer that sets the number of threads on the source
+   shard and the receiving shard for :ref:`chunk migration
+   <migrate-chunks-sharded-cluster>`.
+   
+   Increasing the concurrency improves chunk migration performance, but
+   also increases the workload and disk IOPS usage on the the source
+   shard and the receiving shard.
+
+   Maximum value is 500. You should typically use fewer than 32 threads
+   unless you are using NVMe (Non-Volatile Memory Express) disks.
+
+   The following example sets ``chunkMigrationConcurrency`` to ``5``:
+
+   .. code-block:: bash
+
+      mongod --setParameter chunkMigrationConcurrency=5
+
+   During runtime, you can also set the parameter with the
+   :dbcommand:`setParameter` command:
+
+   .. code-block:: javascript
+
+      db.adminCommand( { setParameter: 1, chunkMigrationConcurrency: 5 } )
+
 .. parameter:: disableResumableRangeDeleter
 
    .. versionadded:: 4.4

source/release-notes/6.3.txt

@@ -82,6 +82,8 @@ Starting in MongoDB 6.3, these server parameters were added:
   the establishment of slow server connections. 
 - :parameter:`connectionAcquisitionToWireLoggingRate` determines when an
   event is added to the log for connection acquisitions.
+- :parameter:`chunkMigrationConcurrency` sets the number of threads on
+  the source shard and the receiving shard for migrating chunks.
 
 Time Series Collection Parameters
 ---------------------------------