> For the complete MongoDB documentation index, see www.mongodb.com/docs/llms.txt

# Remove Shards from a Sharded Cluster

To remove a [shard](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-shard) you must ensure the shard's data is migrated to the remaining shards in the cluster. This procedure describes how to safely migrate data and remove a shard.

## About this Task

- Creating, sharding, or moving collections while performing this procedure may cause interruptions and lead to unexpected results.

- Do not use this procedure to migrate an entire cluster to new hardware. To migrate, see [Migrate a Self-Managed Sharded Cluster to Different Hardware.](https://www.mongodb.com/docs/manual/tutorial/migrate-sharded-cluster-to-new-hardware.md#std-label-migrate-cluster-to-different-hardware)

- When you remove a shard in a cluster with an uneven chunk distribution, the balancer first removes the chunks from the draining shard and then balances the remaining uneven chunk distribution.

- Removing a shard may cause an open [change stream cursor](https://www.mongodb.com/docs/manual/changestreams.md#std-label-changeStreams) to close, and the closed change stream cursor may not be fully resumable.

- You can safely restart a cluster during a shard removal process. If you restart a cluster during an ongoing [draining](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-draining) process, draining continues automatically after the cluster components restart. MongoDB records the shard draining status in the [`config.shards`](https://www.mongodb.com/docs/manual/reference/config-database.md#mongodb-data-config.shards) collection.

## Before you Begin

1. This procedure uses the [`sh.moveCollection()`](https://www.mongodb.com/docs/manual/reference/method/sh.movecollection.md#mongodb-method-sh.moveCollection) method to move collections off of the removed shard. Before you begin this procedure, review the `moveCollection` [considerations](https://www.mongodb.com/docs/manual/reference/method/sh.movecollection.md#std-label-moveCollection-method-considerations) and [requirements](https://www.mongodb.com/docs/manual/reference/method/sh.movecollection.md#std-label-moveCollection-method-reqs) to understand the command behavior.

2. To remove a shard, first connect to one of the cluster's [`mongos`](https://www.mongodb.com/docs/manual/reference/program/mongos.md#mongodb-binary-bin.mongos) instances using [`mongosh`.](https://www.mongodb.com/docs/mongodb-shell.md#mongodb-binary-bin.mongosh)

**Note:**

When removing multiple shards, remove them simultaneously rather than one at a time. Removing one shard at a time causes the balancer to drain data into other remaining shards. A shard can only participate in one chunk migration at a time, so removing one shard limits the throughput of data migration.

## Steps

1. Ensure the balancer is enabled.

   To migrate data from a shard, the [balancer](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-balancer) process must be enabled. To check the balancer state, use the [`sh.getBalancerState()`](https://www.mongodb.com/docs/manual/reference/method/sh.getbalancerstate.md#mongodb-method-sh.getBalancerState) method:

   ```javascript
   sh.getBalancerState()
   ```

   If the operation returns `true`, the balancer is enabled.

   If the operation returns `false`, see [Enable the Balancer.](https://www.mongodb.com/docs/manual/tutorial/manage-sharded-cluster-balancer.md#std-label-sharding-balancing-enable)

2. Determine the name of the shard to remove.

   To find the name of the shard, run the [`listShards`](https://www.mongodb.com/docs/manual/reference/command/listshards.md#mongodb-dbcommand-dbcmd.listShards) command:

   ```javascript
   db.adminCommand( { listShards: 1 } )
   ```

   The `shards._id` field contains the shard name.

3. Start draining the shard.

   Run the [`startShardDraining`](https://www.mongodb.com/docs/manual/reference/command/startsharddraining.md#mongodb-dbcommand-dbcmd.startShardDraining) command to start moving chunks from the sharded collections to the other shards in the cluster:

   ```javascript
   db.adminCommand( { startShardDraining: "shard04" } )
   ```

   If you need to remove multiple shards, you can start the draining processes to run in parallel.

4. Move collections.

   When you create a collection on [`mongos`](https://www.mongodb.com/docs/manual/reference/program/mongos.md#std-program-mongos) and don't call [`shardCollection`](https://www.mongodb.com/docs/manual/reference/command/shardcollection.md#mongodb-dbcommand-dbcmd.shardCollection), that collection remains unsharded and MongoDB stores it in full on a particular shard in the cluster. Databases that use the shard as a primary, also store their collections on the shard.

   If the shard you want to remove contains an unsharded collection or a primary database, you need to move the collection to another shard.

   To identify whether the shard you want to remove contains these collection and to see the draining status, run the [`shardDrainingStatus`](https://www.mongodb.com/docs/manual/reference/command/sharddrainingstatus.md#mongodb-dbcommand-dbcmd.shardDrainingStatus) command and check the array for the `collectionsToMove` output field:

   ```javascript
   db.adminCommand( { shardDrainingStatus: "shard04" } )
   ```

   **Output:**

   ```javascript
   {
      msg: "draining ongoing",
      state: "ongoing",
      remaining: {
         chunks: Long(2),
         dbs: Long(2),
         jumboChunks: Long(0),
         collectionsToMove: Long(2)
      },
      shard: "shard04",
      note: "you need to call moveCollection for collectionsToMove and afterwards movePrimary for the dbsToMove",
      dbsToMove: [
         "accounts",
      ],
      collectionsToMove: [
         "accounts.us-east",
         "accounts.us-west",
         "locations.us",
      ],
      ok: 1,
      operationTime: Timestamp(1575399086, 1655),
      $clusterTime: {
         clusterTime: Timestamp(1575399086, 1655),
         signature: {
            hash: BinData(0,"XBrTmjMMe82fUtVLRm13GBVtRE8="),
            keyId: Long("6766255701040824328")
         }
      }
   }
   ```

   Any collection found in the `collectionsToMove` field is a collection stored on this shard. Before you can remove the shard, you must first move these collections to another shard.

   To move a collection to another shard, use the [`moveCollection`](https://www.mongodb.com/docs/manual/reference/command/movecollection.md#mongodb-dbcommand-dbcmd.moveCollection) command:

   ```javascript
   db.adminCommand( {
      moveCollection: "accounts.us-east",
      toShard: "shard05"
   } )
   ```

5. Move primaries.

   Sharded clusters designate a specific shard to serve as the primary shard for a database. If the shard you want to remove is a primary, you need to move it to a different shard.

   To identify primaries, run the [`shardDrainingStatus`](https://www.mongodb.com/docs/manual/reference/command/sharddrainingstatus.md#mongodb-dbcommand-dbcmd.shardDrainingStatus) command and check the array on the `dbsToMove` output field.

   ```javascript
   db.adminCommand( { shardDrainingStatus: "shard04" } )
   ```

   **Output:**

   ```javascript
   {
      msg: "draining ongoing",
      state: "ongoing",
      remaining: {
         chunks: Long(2),
         dbs: Long(2),
         jumboChunks: Long(0),
         collectionsToMove: Long(2)
      },
      shard: "shard04",
      note: "you need to call moveCollection for collectionsToMove and afterwards movePrimary for the dbsToMove",
      dbsToMove: [
         "accounts",
      ],
      collectionsToMove: [ ],
      ok: 1,
      operationTime: Timestamp(1575399086, 1655),
      $clusterTime: {
         clusterTime: Timestamp(1575399086, 1655),
         signature: {
            hash: BinData(0,"XBrTmjMMe82fUtVLRm13GBVtRE8="),
            keyId: Long("6766255701040824328")
         }
      }
   }
   ```

   Each database shown in the `dbsToMove` field is a database you need to move onto a different shard.

   To move the database, use the [`movePrimary`](https://www.mongodb.com/docs/manual/reference/command/moveprimary.md#mongodb-dbcommand-dbcmd.movePrimary) command:

   ```javascript
   db.adminCommand( {
      movePrimary: "accounts",
      to: "shard05"
   })
   ```

6. Remove the shard.

   Before you remove the shard, check that the draining operation is complete.

   To check the status of the draining operation, run the [`shardDrainingStatus`](https://www.mongodb.com/docs/manual/reference/command/sharddrainingstatus.md#mongodb-dbcommand-dbcmd.shardDrainingStatus) command:

   ```javascript
   db.adminCommand( { shardDrainingStatus: "shard04" } )
   ```

   **Output:**

   ```javascript
   {
      "msg" : "draining completed successfully",
      "state" : "drainingComplete",
      "ok" : 1,
      "$clusterTime" : {
         "clusterTime" : Timestamp(1771839836, 139),
         "signature" : {
            "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
            "keyId" : NumberLong(0)
         }
      },
      "operationTime" : Timestamp(1771839836, 139)
   }
   ```

   When the `state` field returns `drainingComplete` for the shard you want to remove, the draining process is complete. You can now remove the shard.

   To remove the shard, run the [`commitShardRemoval`](https://www.mongodb.com/docs/manual/reference/command/commitshardremoval.md#mongodb-dbcommand-dbcmd.commitShardRemoval) command:

   ```javascript
   db.adminCommand( { commitShardRemoval: "shard04" } )
   ```

   **Output:**

   ```javascript
   {
      "ok" : 1,
      "$clusterTime" : {
         "clusterTime" : Timestamp(1771840037, 12),
         "signature" : {
            "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
            "keyId" : NumberLong(0)
         }
      },
      "operationTime" : Timestamp(1771840037, 12)
   }
   ```

   If the shard is not completely drained, the command returns an error.

## Learn More

- [Add a Member to a Shard](https://www.mongodb.com/docs/manual/tutorial/add-member-to-shard.md#std-label-sharding-procedure-add-member-to-shard)

- [Back Up Self-Managed Cluster Metadata](https://www.mongodb.com/docs/manual/tutorial/backup-sharded-cluster-metadata.md#std-label-back-up-sharded-cluster-metadata)

- [Data Partitioning with Chunks](https://www.mongodb.com/docs/manual/core/sharding-data-partitioning.md#std-label-sharding-data-partitioning)