Scaling Storage Space

Scenarios

If the original storage space is insufficient as your services grow, you can scale up storage space of your DB instance.

When the storage usage is greater than or equal to 97%, the DB instance status changes to Storage full. Your connection to the instance is intermittently interrupted and the instance becomes read-only. When this happens, data cannot be written to the instance.

A DB instance needs to preserve at least 15% of its capacity to work properly. The new minimum storage space required to make this instance available has been automatically calculated for you. You are advised to set alarm rules for the Storage Space Usage metric to learn about the storage usage in a timely manner. For details, see Setting Alarm Rules.

During the scale-up period, services are not interrupted.

Constraints on Scale-up

• You can scale up storage space only when your account balance is greater than or equal to $0 USD.
• The maximum allowed storage is 4,000 GB. There is no limit on the number of scale-ups.
• For primary/standby DB instances, scaling up the primary DB instance will cause the standby DB instance to also be scaled up.
• A DB instance cannot be deleted during scale-up.
• The storage space of a DB instance can be scaled up or down.
• If you scale up a DB instance with the disk encrypted, the expanded storage space will be encrypted using the original encryption key.

Constraints on Scale-down

• The storage space of a DB instance can be scaled only when the instance is Available.
• Only instances whose storage type is cloud SSD or ultra-high I/O can be scaled down.
• If the specifications of a read replica are less than those of the primary instance, scaling down the storage space of the primary instance may fail. It is recommended that the specifications of read replicas be no less than those of the primary instance.
• Scaling down storage space of a DB instance during peak hours may fail due to insufficient storage space. Scale down storage space during off-peak hours.
• To restore from a backup created before scale-down to an existing instance, select an instance whose storage is at least equal to that of the original instance before the scale-down.
• DB instances with snapshot backup enabled cannot be scaled down.
• During scale-down, 40 GB space is reserved to prevent the disk from becoming read-only, so your DB instance can be scaled down only when its available storage space is at least 40 GB.
• For primary/standby instances, scaling down the primary instance will cause the standby instance to also be scaled down.
• A DB instance cannot be deleted during scale-down.
• If you scale down a DB instance with the disk encrypted, the new storage space will be encrypted using the original encryption key.
• The time required for storage scale-down (during off-peak hours) is as follows:
  • The time required depends on how much data there is in your instance. More data means more time.
  • If the scale-down takes an extended period of time, contact customer service.

Billing

Scaling the Storage Space of a DB Instance

1. Log in to the management console.
2. Click in the upper left corner and select a region.
3. Click in the upper left corner of the page and choose Databases > Relational Database Service.
4. On the Instances page, locate the target DB instance and choose More > Scale Storage Space in the Operation column.

   Or use either of the following methods:

   • Click the instance name to go to the Overview page. In the Storage & Backup area, click Scale Storage Space.
   • If the instance storage is full, locate the instance on the Instances page and click Scale in the Status column.

5. On the displayed page, specify the new storage space and click Next.

   You can increase or decrease the storage by at least 10 GB. Enter a value that is a multiple of 10. The instance supports a storage space range from 40 GB to 4,000 GB.

   The final storage space range on the console may differ slightly. It varies with the storage usage of the instance.

6. Confirm the information.
   • If you need to modify your settings, click Previous.
   • If you do not need to modify your settings, click Submit for a pay-per-use instance or click Pay Now for a yearly/monthly instance.

7. Check the result.

   Scaling storage space takes 3-5 minutes. During this period, the status of the DB instance on the Instances page will be Scaling up or Scaling down. After a while, click the instance name and check that the new value for storage space appears on the Overview page.

Scaling the Storage Space of a Read Replica

Scaling the storage space of a read replica does not affect that of the primary DB instance. You can separately scale read replicas to meet service requirements. New storage space of read replicas after scaling must be greater than or equal to that of the primary DB instance.

1. Log in to the management console.
2. Click in the upper left corner and select a region.
3. Click in the upper left corner of the page and choose Databases > Relational Database Service.
4. On the Instances page, locate the target DB instance and click in front of it. Locate the read replica to be scaled and choose More > Scale Storage Space in the Operation column.

   Or use either of the following methods:

   • Click the read replica name to go to the Overview page. In the Storage & Backup area, click Scale Storage Space.
   • If the storage of the read replica is full, locate the read replica on the Instances page and click Scale in the Status column.

5. On the displayed page, specify the new storage space and click Next.

   The minimum start value of each scaling is 10 GB. A read replica can be scaled up or down only by a multiple of 10 GB. The allowed minimum and maximum storage spaces are 40 GB and 4,000 GB, respectively.

   The storage space range varies with the storage usage of the read replica. For details, see the information displayed on the console.

6. Confirm the information.
   • If you need to modify your settings, click Previous.
   • If you do not need to modify your settings, click Submit for a pay-per-use read replica or click Pay Now for a yearly/monthly read replica.

7. Check the result.

   Scaling storage space takes 3-5 minutes. During this period, the status of the read replica on the Instances page will be Scaling up or Scaling down. After a while, click the read replica name and check the new storage space on the displayed Overview page to verify that the scaling is successful.