Isdbgrid documentation

source/core/sharding-internals.txt

@@ -511,6 +511,27 @@ member has replicated changes before allowing new chunk migrations.
 .. _config-database: 
 .. _sharding-internals-config-database:
 
+Determine if You are Connected to a :program:`mongos`
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If your application must determine whether it is connected to a
+:program:`mongos`, use the :dbcommand:`isMaster` command. If the
+application is connected to a :program:`mongos`, the :dbcommand:`isMaster`
+command returns a document with the string ``isdbgrid`` in the ``msg``
+field. For example:
+
+.. code-block:: javascript
+
+   {
+      "ismaster" : true,
+      "msg" : "isdbgrid",
+      "maxBsonObjectSize" : 16777216,
+      "ok" : 1
+   }
+
+If the application is instead connected to a :program:`mongod`, the
+returned document does not include the ``isdbgrid`` string.
+
 Config Database
 ---------------
 

source/reference/command/isdbGrid.txt

@@ -1,26 +1,41 @@
 ========
-isdbGrid
+isdbgrid
 ========
 
 .. default-domain:: mongodb
 
-.. dbcommand:: isdbGrid
+.. dbcommand:: isdbgrid
 
-   Use this command to determine if the process is a :program:`mongos`
-   or a :program:`mongod`. Consider the following command prototype:
+   This command verifies that a process is a :program:`mongos`.
+
+   If you issue the :dbcommand:`isdbgrid` command when connected to a
+   :program:`mongos`, the response document includes the ``isdbgrid``
+   field set to ``1``. The returned document is similar to the
+   following:
 
    .. code-block:: javascript
 
-      { isdbGrid: 1 }
+      { "isdbgrid" : 1, "hostname" : "app.example.net", "ok" : 1 }
 
-   If connected to a :program:`mongos`, the response document
-   resembles the following:
+   If you issue the :dbcommand:`isdbgrid` command when connected to a
+   :program:`mongod`, MongoDB returns an error document. The
+   :dbcommand:`isdbgrid` command is not available to :program:`mongod`.
+   The error document, however, also includes a line that reads
+   ``"isdbgrid" : 1``, just as in the document returned for a
+   :program:`mongos`. The error document is similar to the following:
 
    .. code-block:: javascript
 
-      { "isdbgrid" : 1, "hostname" : "app.example.net", "ok" : 1 }
-
-   You can also use the :dbcommand:`isMaster` command, which when
-   connected to a :program:`mongos`, contains the string
-   ``isdbgrid`` in the ``msg`` field of its output document.
+      {
+         "errmsg" : "no such cmd: isdbgrid",
+         "bad cmd" : {
+               "isdbgrid" : 1
+         },
+         "ok" : 0
+      }
+
+   You can instead use the :dbcommand:`isMaster` command to determine
+   connection to a :program:`mongos`. When connected to a
+   :program:`mongos`, the :dbcommand:`isMaster` command returns a document that
+   contains the string ``isdbgrid`` in the ``msg`` field.