You can manually add or remove read-only nodes after creating an ApsaraDB for POLARDB cluster. An ApsaraDB for POLARDB cluster can contain a maximum of 15 read-only nodes. The cluster must have at least one read-only node to guarantee high availability. All nodes in a cluster have the same specifications.

Billing

The billing methods for nodes added to an existing cluster are as follows:
  • If nodes are added to a subscription cluster, the nodes are billed as subscription nodes.
  • If nodes are added to a pay-as-you-go cluster, the nodes are billed as pay-as-you-go nodes.
Note
  • Read-only nodes that you purchase in either subscription or pay-as-you-go mode can be released at any time. After they are released, the system will refund or stop billing.
  • The added nodes are only charged based on the node specifications. For more information, see Specifications and pricing. The storage fee is charged based on the actual data volume, regardless of the number of nodes.

Precautions

  • You can only add or remove read-only nodes when the cluster does not have pending specification changes.
  • To avoid misoperations, only one read-only node can be added or removed at a time. You must perform the add or remove operation for each node.
  • It takes about 5 minutes to add or remove a node.

Add a read-only node

  1. Log on to the ApsaraDB for POLARDB console.
  2. Select a region.
  3. Go to the Add/Remove Node page. Perform the operation by using either of the following methods:
    • Find the target cluster and click Add/Remove Node in the Actions column.
      Add/Remove Node button
    • Find the target cluster, click the cluster ID, and then click Add/Remove Node in the Node Information section.
      Add/Remove Node button
  4. Select Add Node and click OK.
    Add/Remove Node dialog box
  5. Click the Add button icon to add a read-only node. Read and agree to the service agreement by selecting the check box, and click Pay to complete the payment.

Remove a read-only node

  1. Log on to the ApsaraDB for POLARDB console.
  2. Select a region.
  3. Go to the Add/Remove Node page. Perform the operation by using either of the following methods:
    • Find the target cluster and click Add/Remove Node in the Actions column.
      Add/Remove Node button
    • Find the target cluster, click the cluster ID, and then click Add/Remove Node in the Node Information section.
      Add/Remove Node button
  4. Select Remove Node and click OK.
    Add/Remove Node dialog box
  5. Click the Remove button icon next to the node that you want to remove. In the dialog box that appears, click OK.
    Note You must keep at least one read-only node in the cluster to guarantee high availability.
  6. Read and agree to the service agreement by selecting the check box, and click OK.

Related API operations

API operation Description
CreateDBNodes Adds a node to an ApsaraDB for POLARDB cluster.
ModifyDBNodeClass Changes the specifications of a node in an ApsaraDB for POLARDB cluster.
RestartDBNode Restarts a node in an ApsaraDB for POLARDB cluster.
DeleteDBNodes Removes a node from an ApsaraDB for POLARDB cluster.