Overview - ApsaraDB for MongoDB - Alibaba Cloud Documentation Center

This topic describes how to change the configurations of an existing instance to better meet your needs by using the corresponding features in the ApsaraDB for MongoDB console.

Configuration change methods

Configuration change methods and change items vary based on instance categories. The following table describes the configuration change methods and change items for different categories of instances.


Configuration change method	Billing method	Change type	Change item
Change the configurations of a standalone instance	Subscription	Upgrade	The Specifications and Storage configurations of an instance can be changed.
	Subscription	Downgrade	The Specifications configuration of an instance can be changed.
	Pay-as-you-go	Upgrade Downgrade	The Specifications and Storage configurations of an instance can be changed. Note When you change the value of the Storage parameter, you must make sure that the new specified storage capacity is greater than or equal to the existing storage capacity of the instance. The storage capacity of ApsaraDB for MongoDB instances cannot be decreased. To decrease the storage capacity of an ApsaraDB for MongoDB instance, you can create another instance to replace the existing one. For more information, see Other configuration change scenarios and methods.
Change the configurations of a replica set instance	Subscription	Upgrade	The Active-standby Nodes, Read-only Nodes, Specifications, and Storage configurations of an instance can be changed. Note The Active-standby Nodes and Read-only Nodes configurations cannot be changed for instances that run MongoDB 5.0 or 4.4. When you change the value of the Storage parameter, you must make sure that the new specified storage capacity is greater than or equal to the existing storage capacity of the instance. After the Storage configuration is changed, the new storage capacity value is applied to each independent node of the instance, not the total storage capacity of all nodes.
	Subscription	Downgrade	The Active-standby Nodes, Read-only Nodes, and Specifications configurations of an instance can be changed. Note The Active-standby Nodes and Read-only Nodes configurations cannot be changed for instances that run MongoDB 5.0 or 4.4.
	Pay-as-you-go	Upgrade Downgrade	The Active-standby Nodes, Read-only Nodes, Specifications, and Storage configurations of an instance can be changed. Note The Active-standby Nodes and Read-only Nodes configurations cannot be changed for instances that run MongoDB 5.0 or 4.4. When you change the value of the Storage parameter, you must make sure that the new specified storage capacity is greater than or equal to the existing storage capacity of the instance. The storage capacity of ApsaraDB for MongoDB instances cannot be decreased. To decrease the storage capacity of an ApsaraDB for MongoDB instance, you can create another instance to replace the existing one. For more information, see Other configuration change scenarios and methods. After the Storage configuration is changed, the new storage capacity value is applied to each independent node of the instance, not the total storage capacity of all nodes.
Overview	Subscription	Add a mongos node	When you add a mongos node, you can set Instance Specifications and Quantity. Note A maximum of 32 mongos nodes can be added to each sharded cluster instance. If the sharded cluster instance already has three mongos nodes and you want to add more mongos nodes, you can add a maximum of 29 mongos nodes to the sharded cluster instance.
		Add a shard node	When you add a shard node, you can set Instance Specifications, Quantity, Storage Capacity, and Read-only Nodes. Note A maximum of 32 shard nodes can be added to each sharded cluster instance. If the sharded cluster instance already has three shard nodes and you want to add more shard nodes, you can add a maximum of 29 shard nodes to the sharded cluster instance. The Instance Specifications, Storage Capacity, and Read-only Nodes values of the added shard node must be greater than or equal to the highest values among existing shard nodes. The storage capacity of the shard node cannot be decreased. To decrease the storage capacity of the shard node, you can create another instance to replace the existing one. For more information, see Other configuration change scenarios and methods. If read-only nodes are added when you create a shard node, the specified storage capacity value is applied to the shard node and each read-only node.
		Change the configurations of one or more mongos nodes	The Instance Specifications configurations of one or more mongos nodes can be changed.
		Change the configurations of one or more shard nodes	The Instance Specifications, Storage Capacity, and Read-only Nodes configurations of one or more shard nodes can be changed. Note When you change the value of the Storage Capacity parameter, you must make sure that the new specified storage capacity is greater than or equal to the existing storage capacity of the instance. The storage capacity of the shard node cannot be decreased. To decrease the storage capacity of the shard node, you can create another instance to replace the existing one. For more information, see Other configuration change scenarios and methods. After the Storage Capacity configuration of a shard node is changed, the new storage capacity value is applied to the shard node and each read-only node.
	Pay-as-you-go	Add a mongos node	When you add a mongos node, you can set Instance Specifications and Quantity. Note A maximum of 32 mongos nodes can be added to each sharded cluster instance. If the sharded cluster instance already has three mongos nodes and you want to add more mongos nodes, you can add a maximum of 29 mongos nodes to the sharded cluster instance.
		Add a shard node	When you add a shard node, you can set Instance Specifications, Quantity, and Storage Capacity. Note A maximum of 32 shard nodes can be added to each sharded cluster instance. If the sharded cluster instance already has three shard nodes and you want to add more shard nodes, you can add a maximum of 29 shard nodes to the sharded cluster instance. When you set the value of the Storage Capacity parameter, you must make sure that the new specified storage capacity is greater than or equal to the existing storage capacity of the instance. The storage capacity of the shard node cannot be decreased. To decrease the storage capacity of the shard node, you can create another instance to replace the existing one. For more information, see Other configuration change scenarios and methods. If read-only nodes are added when you create a shard node, the specified storage capacity value is applied to the shard node and each read-only node.
		Change the configurations of one or more mongos nodes	The Instance Specifications configurations of one or more mongos nodes can be changed.
		Change the configurations of one or more shard nodes	The Instance Specifications and Storage Capacity configurations of one or more shard nodes can be changed. Note When you change the value of the Storage Capacity parameter, you must make sure that the new specified storage capacity is greater than or equal to the existing storage capacity of the instance. The storage capacity of the shard node cannot be decreased. To decrease the storage capacity of the shard node, you can create another instance to replace the existing one. For more information, see Other configuration change scenarios and methods. After the Storage Capacity configuration of a shard node is changed, the new storage capacity value is applied to the shard node and each read-only node.
		Release a mongos or shard node	You can manually release a mongos or shard node. Note You can manually release a mongos node for a sharded cluster instance that has at least three mongos nodes, but you must make sure that the sharded cluster instance has at least two mongos nodes after the release. You can manually release a shard node for a sharded cluster instance that has at least three shard nodes, but you must make sure that the sharded cluster instance has at least two shard nodes after the release. Before you release a shard node from a sharded cluster instance, make sure that the data of the shard node can be offloaded onto the remaining shard nodes in the sharded cluster instance. Otherwise, the sharded cluster instance will remain in the Deleting Node state after you attempt to release a shard node. In this case, you cannot perform operations such as resetting the password, switching node roles, modifying the node connection string, or modifying parameters.

Other configuration change scenarios and methods

You may encounter the following configuration change scenarios:

Downgrade the storage capacity of an instance or a shard node.
Add the number of nodes for a standalone instance.
Change the architecture of an instance.
Change the storage engine from RocksDB or TerarkDB to WiredTiger.

When you encounter the preceding scenarios, you can perform the following steps to change the configurations:

Create an instance. For more information, see Create a standalone instance, Create a replica set instance, or Create a sharded cluster instance.
Note
- If you want to decrease the storage capacity by creating another instance, the storage capacity of the new instance must be greater than the amount of capacity used by the source instance.
- If you want to change the number of nodes by creating another instance, you must create a replica set instance.
- If you want to change the instance architecture by creating another instance, you must choose an instance category specific to the desired architecture. For more information about the instance architecture, see Architecture of ApsaraDB for MongoDB.
- In backup and restoration scenarios, you can clone an instance to create another instance. For more information, see Restore backup data to a new ApsaraDB for MongoDB instance by point in time or Restore backup data to a new ApsaraDB for MongoDB instance by backup point.
Migrate the data of the source instance to the new instance. For more information, see Overview.
After you verify functionality of the new instance, switch business from the source instance to the new instance.
Optional: If you no longer need the source instance, release the instance.
- For a subscription instance, you cannot manually release the instance.
- For a pay-as-you-go instance, you can manually release the instance. For more information, see Release an instance or a node.

References

For more information about MongoDB versions, storage engines, and the relationship between MongoDB versions and storage engines, see MongoDB versions and storage engines.

For more information about how to upgrade the MongoDB version of an instance, see Upgrade the major version of an ApsaraDB for MongoDB instance.