mongodump --out <exportDataDestination> 

Specify additional options as appropriate, such as username and password if running with authorization enabled. See mongodump for available options. 

Step 14: For the first config server, create data directory for WiredTiger. Ensure that the user account running mongod has read and write permissions for the new directory. 

mongod with WiredTiger will not start if the --dbpath directory contains data files created with a different storage engine. 

Step 15: Restart the first config server with WiredTiger. Specify wiredTiger as the --storageEngine and the newly created WiredTiger data directory as the --dbpath as well as any additional options as appropriate. 

mongod --storageEngine wiredTiger --dbpath <newWiredTigerDBPath> --configsvr 

You can also specify the options in a configuration file . To specify the storage engine, use the new storage.engine setting. 

## Step 16: Upload the exported data using mongorestore to the first config server. 

mongorestore <exportDataDestination> 

Specify additional options as appropriate. See mongorestore for available options 

Step 17: Enable writes to the sharded cluster’s metadata. Restart the second config server, specifying WiredTiger as the --storageEngine and the newly created WiredTiger data directory as the --dbpath . Specify additional options as appropriate. 

mongod --storageEngine wiredTiger --dbpath <newWiredTigerDBPath> --configsvr 

You can also specify the options in a configuration file . To specify the storage engine, use the new storage.engine setting. 

Once all three config servers are up, the sharded cluster’s metadata is available for writes. 

Step 18: Re-enable the balancer. Once all three config servers are up and running with WiredTiger, Re-enable the balancer (page 718). 

Upgrade Existing MONGODB-CR Users to Use SCRAM-SHA-1 After upgrading the binaries, see Upgrade to SCRAM-SHA-1 (page 818) for details on SCRAM-SHA-1 upgrade scenarios. 

General Upgrade Procedure Except as described on this page, moving between 2.6 and 3.0 is a drop-in replace- ment: 

Step 1: Stop the existing mongod instance. For example, on Linux, run 2.6 mongod with the --shutdown option as follows: 

mongod --dbpath /var/mongod/data --shutdown 

Replace /var/mongod/data with your MongoDB dbPath . See also the Stop mongod Processes (page 225) for alternate methods of stopping a mongod instance. 

