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Change Sharded Cluster to WiredTiger

Starting in version 3.2, WiredTiger is the default storage engine for MongoDB. Use this tutorial to update your 3.2 sharded clusters to use WiredTiger.

To convert a 3.0 sharded cluster that uses MMAPv1, see the MongoDB 3.0 manual.



This procedure may involve downtime, especially if one or more of your shards is a standalone. If you change the host or port of any shard, you must update the shard configuration as well.

MongoDB 3.0 or Greater

You must be using MongoDB version 3.0 or greater in order to use the WiredTiger storage engine. If upgrading from an earlier version of MongoDB, see the guides on Upgrading to MongoDB 3.0 or Upgrading to MongoDB 3.2 before proceeding with changing your storage engine.

Change Shards to WiredTiger


A sharded cluster can have mixed storage engines for its individual shards.

To change the storage engine for the shards to WiredTiger, refer to the appropriate procedure for each shard:

Change Config Servers to WiredTiger


Starting in MongoDB 3.2, config servers can be deployed as replica sets. If the config servers are deployed as a replica set (CSRS), the config servers already use WiredTiger.

Mirrored mongod Instances

If the config servers are deployed as 3 mirrored mongod instances, see Change Config Servers to WiredTiger to change the storage engines of these config servers.

You may safely continue to use MMAPv1 for the config servers even if one or more shards in the sharded cluster are using the WiredTiger storage engine. If you do choose to update the config servers to use WiredTiger, you must update all three.