(DOCSP-23054): File copy based initial sync improvements (#1193)

* (DOCSP-23054): File copy based initial sync improvements

* reordering

* wording

* clarify local db limitation

* members > member

Author: jeff-allen-mongo

source/core/replica-set-sync.txt

@@ -71,14 +71,12 @@ To perform an initial sync, see
 File Copy Based Initial Sync
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-File copy based initial sync runs the initial sync process by copying
-and moving files on the file system. 
+*Available in MongoDB Enterprise only.*
 
-File copy based initial sync can be faster than 
+File copy based initial sync runs the initial sync process by copying
+and moving files on the file system. This sync method can be faster than
 :ref:`logical initial sync <replica-set-initial-sync-logical>`.
 
-It is only available on Enterprise Server.
-
 .. important:: File copy based initial sync may cause inaccurate counts
 
    After file copy based initial sync completes, if you run the
@@ -90,29 +88,36 @@ It is only available on Enterprise Server.
 
    To learn more, see :ref:`count-method-behavior-query-predicate`.
 
-Limitations
-```````````
+Enable File Copy Based Initial Sync
+```````````````````````````````````
 
-- File copy based initial sync replaces the ``local`` database on the 
-  node being *synced to* with the ``local`` database from the node 
-  being *synced from*.
+To enable file copy based initial sync, set the
+:parameter:`initialSyncMethod` parameter to ``fileCopyBased`` on the
+destination member for the initial sync. This parameter can only be set
+at startup.
 
-- You can only run an initial sync from one given node at a time. 
+Behavior
+````````
 
-- You cannot run a backup on the node that is being *synced to* during 
-  the initial sync.
+File copy based initial sync replaces the ``local`` database on the
+member being *synced to* with the ``local`` database from the member
+being *synced from*.
 
-- You cannot run a backup on the node that is being *synced from* during 
-  the initial sync.
+Limitations
+```````````
 
-- You cannot use file copy based initial sync with encrypted storage  
-  engine to re-key the data.
+- During a file copy based initial sync:
 
-.. warning::
+  - You cannot run a backup on the member that is being *synced to* or
+    the member that is being *synced from*.
 
-   You cannot write to the ``local`` database during a file copy based
-   sync.
+  - You cannot write to the ``local`` database on the member that is being
+    *synced to*.
 
+- You can only run an initial sync from one given member at a time. 
+
+- You cannot use file copy based initial sync with encrypted storage
+  engine to re-key the data.
 
 .. _init-sync-retry:
 

source/reference/parameters.txt

@@ -2471,24 +2471,26 @@ If you attempt to update ``disableSplitHorizonIPCheck`` at runtime,
 
    *Type*: String                                                           
 
-   *Default*: ``logical``                                                   
+   *Default*: ``logical``   
+
+   Available only in MongoDB Enterprise.                                                
 
    Method used for :ref:`initial sync <replica-set-initial-sync>`.          
 
    Set to ``logical`` to use :ref:`logical initial sync                     
    <replica-set-initial-sync-logical>`. Set to ``fileCopyBased`` to         
    use :ref:`file copy based initial sync                                   
-   <replica-set-initial-sync-file-copy-based>`.                             
+   <replica-set-initial-sync-file-copy-based>`.     
+
+   This parameter only affects the sync method for the member on which
+   it is specified. Setting this parameter on a single replica set
+   member does not affect the sync method of any other replica set
+   members.                        
 
    You can only set this parameter on startup, using either the             
    :setting:`setParameter` configuration file setting or the                
    :option:`--setParameter <mongod --setParameter>` command line option.
 
-   .. note::                                                                
-
-      Available only in MongoDB Enterprise. 
-
-
 .. parameter:: maxNumSyncSourceChangesPerHour
 
    .. versionadded:: 5.0
@@ -4718,4 +4720,3 @@ Slot-Based Execution Parameters
    .. code-block:: javascript
 
       db.adminCommand( { setParameter: 1, planCacheSize: "80MB" } )
-