Creating a Real-Time DR Task

Operation Process

Preparations

Before creating a real-time DR task, prepare the Huawei account, database to be migrated, database connection account, and network environment by referring to the following steps.

Step 1: Create a DR Task

This step describes how to set parameters based on the example values in Preparations. For more information about real-time disaster recovery, see DR Overview.

1. Go to the Create Disaster Recovery Task page.
2. Configure basic information as follows:
   Figure 1 Basic information
   

   Parameter	Example Value	Description
   Billing Mode	Pay-per-use	DRS billing mode. Yearly/Monthly: A prepaid billing mode in which you pay for resources before using it. Bills are settled based on the subscription period. Pay-per-use billing: A postpaid billing mode. In this mode, you pay for what you used.
   Region	AP-Singapore	The region where the current task is deployed.
   Project	AP-Singapore	The project corresponds to the current region.
   Task Name	DRS-DRTask	The name of the DR task.
   Description	Leave this parameter blank for now.	Task description.

3. Configure information about the disaster recovery instance.
   Figure 2 Disaster recovery instance details
   

   Parameter	Example Value	Description
   Disaster Recovery Relationship	Current cloud as standby	The disaster recovery relationship of the DR task. The options are Current cloud as standby and Current cloud as active. Current cloud as standby: The DR database is a Huawei Cloud DB instance and data needs to be transferred to the cloud. Current cloud as active: The service database is a Huawei Cloud DB instance and data needs to be transferred out of the cloud.
   Service DB Engine	MySQL	The DB engine type of the service database.
   DR DB Engine	MySQL	The DB engine type of the DR database.
   Network Type	Public network	The network type of the DR task.
   DRS Task Type	Single-AZ	Type of the DRS task. The value can be Single-AZ or Dual-AZ.
   DR DB Instance	rds-DRtar	Select a DR DB instance. The DR DB instance is rds-DRtar in Databases.
   Disaster Recovery Instance Subnet	Default subnet	The subnet where the DR task is.
   Destination DB Instance Access	Read-only	During the disaster recovery, set the DR DB instance to the read-only state.
   Enable Binlog Cleanup	No	Whether to enable the function of quickly clearing binlogs of the DR database.
   Specify EIP	-	Select an EIP for the DRS instance. In this example, it is the EIP created in Network.

4. Select the task specifications and AZ.
   Figure 3 Specifications and AZ
   

   Parameter	Example Value	Description
   Specifications	Large	DRS instance specifications. Different specifications have different performance upper limits. For details, see Real-Time DR.
   AZ	AZ1	Select the AZ where you want to create the DRS task.

5. Configure an enterprise project and tags.
   Figure 4 Enterprise Project and Tags
   

   Parameter	Example Value	Description
   Enterprise Project	default	If your account is associated with an enterprise project, select the project from the Enterprise Project drop-down list. For more details, see Enterprise Management User Guide.
   Tags	Leave this parameter blank for now.	Tags for the DR task. Adding tags helps you better identify and manage your tasks.

6. Click Create Now.

   Wait for 5 to 10 minutes. If the message "Disaster recovery instance created successfully" is displayed, the DRS task is successfully created.

7. On the Configure Source and Destination Databases page, specify source and destination database details and click Test Connection for both the source and destination databases to confirm they have been connected to the DRS instance.
   1. In the Source Database area, enter the source database details in Connection Accounts.
   2. Click Test Connection.

      If the message "Test successful" is displayed, the source database is connected.

   3. In the Destination Database area, enter the destination database details in Connection Accounts.
   4. Click Test Connection.

      If the message "Test successful" is displayed, the destination database is connected.

   5. Click Next.

8. On the Configure DR page, specify flow control and click Next.
   • Set Flow Control to No.
   • Set Migrate Definer to User to Yes.
     Figure 5 DR settings
     

     Parameter	Example Value	Description
     Flow Control	No	Whether to set a maximum speed for the DR task. This function is disabled by default.
     Migrate Definer to User	Yes	Whether to migrate the Definers of all source database objects to the destination database user entered during the connection test.

9. On the Check Task page, check the DR task.
   • If there are any items that require confirmation, view and confirm the details first before proceeding to the next step.
   • If any of the checks fail, review the cause and rectify the fault. After the fault is rectified, click Check Again.

   If the check success rate reaches 100%, the pre-check is successful.

10. Click Next
11. On the Compare Parameters page, compare and modify common and performance parameters.
    • If you do not want to compare parameters or the parameters of the source database are the same as those of the destination database, skip this step.
    • If the parameters of the source database are inconsistent with those of the destination database, you can manually change the values of the destination database parameters or click Use Source Database Value to make the parameter values of the source and destination database be the same.

12. Click Next
13. On the Confirm Task page, specify Start Time.
    Figure 6 Task startup settings
    

    Parameter	Example Value	Description
    Start Time	Start upon task creation	Set Start Time to Start upon task creation or Start at a specified time based on site requirements. The Start at a specified time option is recommended.
    Send Notifications	Disable	This parameter is optional. After enabled, select an SMN topic. If the status, latency metric, or data of the DR task is abnormal, DRS will send you a notification.
    Stop Abnormal Tasks After	14	Any task in the Abnormal state that has run for longer than the period you set here (in days) will automatically stop.

14. Confirm that the configured information is correct and click Submit to submit the task.
15. After the DR task is submitted, go to the Disaster Recovery Management page to check the task status.
    • If the task status is Starting, the task has been started.
    • By default, DRS retains a task in the Configuration state for three days. After three days, DRS automatically deletes background resources, but the task status remains unchanged. When you reconfigure the task, DRS applies for resources for the task again.

Step 2: Query DR Progress

After the DR task is started, you can check the DR progress. DRS shows the DR progress using a progress bar, so you can track the DR progress in real time.

1. On the Disaster Recovery Management page, click the target DR task in the Task Name/ID column.

   The Basic Information page is displayed.

2. Choose Disaster Recovery Progress to check the progress.
   • When the data initialization is complete, the initialization progress is displayed as 100%.
   • Delay refers to the delay from when the transaction was submitted to the source database to when it is synchronized to the destination database and executed.

     When the delay is 0, data is synchronized from the service database to the DR database in real time. You can view more metrics, such as RPO and RTO, on the Disaster Recovery Monitoring tab.

3. When the delay of the DR task is 0s, you can use data comparison to check whether the data in the service database is consistent with that in the DR database.

Step 3: Compare DR Items

When the task enters the Disaster recovery in progress state and the RPO and RTO are 0, you can create a comparison task to check whether the data in the source database is consistent with that in the destination database.

• Object-level comparison: It compares databases, indexes, tables, views, stored procedures and functions, and sorting rules of tables. You are advised to perform an object-level comparison first.
• Data-level comparison: It checks the consistency of rows or values in the migration tables.

Step 4 (Optional): Perform a DR Switchover

DRS allows you to perform a switchover for a DR task. When a disaster occurs, the DR database can be promoted to the service database to ensure service continuity.

• Before a switchover, services are running properly in the service database and data is synchronized to the DR database in real time. In this case, data cannot be written into the DR database.
• After a switchover, the DR database becomes readable and writable, services can be switched to the DR database, and data cannot be written to the service database.

1. On the Disaster Recovery Management page, locate the target DR task.
2. Click the task name.

   The Basic Information page is displayed.

3. Choose Disaster Recovery Progress to check the RPO and RTO.
   • RPO measures the difference between the data in the service database and the data in the DRS instance. When RPO is 0, all the data in the service database has been migrated to the DRS instance.
   • RTO measures the amount of data being transmitted. When RTO is 0, all transactions on the DRS instance have been completed on the DR database.

   If both RPO and RTO are 0, data has been completely migrated to the DR database. Then, you can determine whether to perform a switchover.

4. Choose Disaster Recovery Monitoring.
5. A switchover can be performed only when the task status is Disaster recovery in progress.
   • Click Promote Current Cloud to promote the current instance to the service database.
   • Click Demote Current Cloud to demote the current instance to the DR database.

   The DR relationship involves only one primary database. During a primary/secondary switchover, ensure that there is no data written to the database that will be the standby node, and no data will be written to the standby node in the future. The data of the standby node is synchronized only from the primary node. Any other write operations will pollute the data in the standby database, data conflicts occur in the database and cannot be resolved.