Configuration change methods supported by ApsaraDB for MongoDB - ApsaraDB for MongoDB

This topic describes how to change the configurations of an existing instance to better meet your business requirements 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	Billable item	Change type	Change item
Change the configurations of a standalone instance	Subscription	Upgrade	The Specification and Storage values of an instance can be changed.
	Subscription	Downgrade	The Specification value of an instance can be changed.
	Pay-as-you-go	Upgrade Downgrade	The Specification and Storage values 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. You cannot reduce the storage capacity of an instance. To reduce the storage capacity of the instance, you can create another instance to replace the existing instance. 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 values 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. After the value of the Storage parameter is changed, the new storage capacity value is applicable to each node of the instance, not the total storage capacity of all nodes.
	Subscription	Downgrade	The Active-standby Nodes, Read-only Nodes, and Specifications values of an instance can be changed.
	Pay-as-you-go	Upgrade Downgrade	The Active-standby Nodes, Read-only Nodes, Specifications, and Storage values 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. You cannot reduce the storage capacity of an instance. To reduce the storage capacity of the instance, you can create another instance to replace the existing instance. For more information, see Other configuration change scenarios and methods. After the value of the Storage parameter is changed, the new storage capacity value is applicable to each node of the instance, not the total storage capacity of all nodes.
Change the configurations of a sharded cluster instance	Subscription	Add a mongos node	When you add a mongos node, you can configure the Instance Specifications and Quantity parameters. Note A maximum of 32 mongos nodes can be added to a 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 configure the Specifications, Quantity, Storage, and Read-only Nodes parameters. Note A maximum of 32 shard nodes can be added to a 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 Specifications, Storage, and Read-only Nodes values of the new shard node must be greater than or equal to the greatest values among existing shard nodes. You cannot reduce the storage capacity of a shard node in an existing instance. To reduce the storage capacity of the node, you can create another instance to replace the existing instance. 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 applicable to the shard node and each read-only node.
		Change the configurations of one or more mongos nodes	The Instance Specifications values 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 values 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. You cannot reduce the storage capacity of a shard node in an existing instance. To reduce the storage capacity of the node, you can create another instance to replace the existing instance. For more information, see Other configuration change scenarios and methods. After the Storage Capacity value of a shard node is changed, the new storage capacity value is applicable to the shard node and each read-only node.
		Change the configurations of the ConfigServer node in a sharded cluster instance	You can change the Instance Specifications and Storage Capacity values of the ConfigServer node in a sharded cluster instance. Note The new specified storage capacity must be greater than or equal to the existing storage capacity of the ConfigServer node. You cannot change the configurations of the ConfigServer node in a sharded cluster instance that uses local disks.
		Change the configurations of multiple mongos, shard, and ConfigServer nodes in batch	You can start a configuration change task for multiple mongos, shard, and ConfigServer nodes in a sharded cluster instance at a time. The task involves the following operations: Change the specifications and storage capacity of one or more shard nodes. Change the specifications of one or more mongos nodes. Change the specifications and storage capacity of the ConfigServer node. Note You cannot change the configurations of the ConfigServer node in a sharded cluster instance that uses local disks. Make sure that the limits on configuration changes for specified mongos, shard, and ConfigServer nodes in the instance are met. To change the number of read-only nodes in a shard node, you must change the configurations of the shard node.
	Pay-as-you-go	Add a mongos node	When you add a mongos node, you can configure the Instance Specifications and Quantity parameters. Note A maximum of 32 mongos nodes can be added to a 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 configure the Specifications, Quantity, and Storage parameters. Note A maximum of 32 shard nodes can be added to a 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 parameter, you must make sure that the new specified storage capacity is greater than or equal to the existing storage capacity of the instance. You cannot reduce the storage capacity of a shard node in an existing instance. To reduce the storage capacity of the node, you can create another instance to replace the existing instance. 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 applicable to the shard node and each read-only node.
		Change the configurations of one or more mongos nodes	The Instance Specifications values of one or more mongos nodes can be changed.
		Change the configurations of one or more shard nodes	The Instance Specifications and Storage Capacity values 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. You cannot reduce the storage capacity of a shard node in an existing instance. To reduce the storage capacity of the node, you can create another instance to replace the existing instance. For more information, see Other configuration change scenarios and methods. After the Storage Capacity value of a shard node is changed, the new storage capacity value is applicable to the shard node and each read-only node.
		Change the configurations of the ConfigServer node in a sharded cluster instance	You can change the Instance Specifications and Storage Capacity values of the ConfigServer node in a sharded cluster instance. Note The new specified storage capacity must be greater than or equal to the existing storage capacity of the ConfigServer node. You cannot change the configurations of the ConfigServer node in a sharded cluster instance that uses local disks.
		Change the configurations of multiple mongos, shard, and ConfigServer nodes in batch	You can start a configuration change task for multiple mongos, shard, and ConfigServer nodes in a sharded cluster instance at a time. The task involves the following operations: Change the specifications and storage capacity of one or more shard nodes. Change the specifications of one or more mongos nodes. Change the specifications and storage capacity of the ConfigServer node. Note You cannot change the configurations of the ConfigServer node in a sharded cluster instance that uses local disks. Make sure that the limits on configuration changes for specified mongos, shard, and ConfigServer nodes in the instance are met. To change the number of read-only nodes in a shard node, you must change the configurations of the shard 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 instance. Otherwise, the 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 to a standalone instance.
Change the architecture of an instance.
Change the storage engine of an instance from RocksDB or TerarkDB to WiredTiger.

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

Create another 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 storage 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 instance architectures, see Architectures and components of ApsaraDB for MongoDB.
- Restore backup data to the new 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 data from the source instance to the new instance. For more information about migration methods for different instance architectures, see Overview.
After you verify the functionality of the new instance, switch over your business from the source instance to the new instance.
Optional: If you no longer need the source instance, release the instance by using one of the following methods:
- 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 ApsaraDB for MongoDB instance.

References

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

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