Scaling Up a Read Replica

Precautions

• Scaling is available when your account balance is sufficient.
• If you scale up a DB instance with disks encrypted, the expanded storage space will be encrypted using the original encryption key.
• An instance cannot be scaled up if it is in any of the following statuses:
  • Creating
  • Changing instance class
  • Adding node
  • Deleting node
  • Upgrading minor version
  • Switchover in progress
• During scaling, services will not be interrupted, and the storage type cannot be changed.

Pricing

• A pay-per-use instance is still billed on an hourly basis after the instance is scaled up.

• If you scale up a yearly/monthly instance, you will pay price difference or get a refund.
• For details, see Product Pricing Details.

Procedure

1. Log in to the management console.
2. Click in the upper left corner and select a region and a project.
3. Click in the upper left corner of the page and choose Databases > Document Database Service.
4. On the Instances page, click the replica set instance name.
5. In the Node Information area on the Basic Information page, locate the read replica you want to scale up and click Scale Storage Space in the Operation column.
   Figure 1 Scaling storage space
   

6. On the displayed page, specify the desired amount of space to be changed and click Next.
   Figure 2 Scaling up a read replica
   

   Select at least 10 GB each time you scale up the storage, and the storage size must be multiples of 10 GB. The maximum amount of storage space is 5,000 GB.

7. On the displayed page, confirm the storage space.
   • For yearly/monthly instances
     • If you need to modify your settings, click Previous to go back to the page for you to specify details.
     • If you do not need to modify your settings, click Submit to go to the payment page and complete the payment.
   • For pay-per-use instances
     • If you need to modify your settings, click Previous to go back to the page for you to specify details.
     • If you do not need to modify the specifications, click Submit to scale up the storage space.

8. Check the results.
   • This process takes about 3 to 5 minutes. The status of the DB instance in the instance list is Scaling up.
   • In the upper right corner of the instance list, click to refresh the list. The instance status changes to Available.
   

   If the storage space is scaled up to more than 4 TB, the following risks may occur:

   1. The larger the data volume, the higher the stress of database query, compaction (to release disk space), and backup, and the more new problems. If the storage space exceeds 4 TB, the database SLA cannot be ensured.
   2. The full backup of an instance may take more than one day. As a result, data may not be backed up in a timely manner.
   3. If data is deleted by mistake, it takes a long time to restore a table to a specified point in time or restore a backup to a new instance, affecting the restoration efficiency.
   4. If the primary/secondary or read-only replication is delayed, it takes a long time to reconnect. As a result, the instance may be disconnected or fail to be connected.

Reference

What Should I Do If Storage Usage Is Unusually High?