Data Transmission Service:Switch workloads to the destination database

Switch workloads to the destination database

1. Wait until the data migration instance enters the Incremental Data Migration stage and the latency in the Running Information column is less than 5 seconds.

   

   Note

   If the migration instance does not have an Incremental Data Migration stage (that is, you do not select Incremental Data Migration for Migration Types when you configure the instance), the instance automatically ends after data migration is complete. Wait until the Status of the instance changes to Completed.

2. Suspend your business and stop writing data to the source database.

3. Log on to the source database and view session information. Make sure that no new sessions are used for write operations.

   Run the following statements based on the source database type:

   MySQL

   show processlist;

   SQL Server

   select * from sys.dm_exec_connections;

   Oracle

   select sid,serial#,username,program,machine,status from v$session;

   PostgreSQL

   select * from pg_stat_activity;

   Redis

   CLIENT LIST

   MongoDB

   use admin
   db.runCommand({currentOp: 1, $all:[{"active" : true}]})

   Note

   The process or session information returned by the preceding statements includes the processes or sessions between DTS and the source database.

4. Pause the data migration instance.

   Important

   • Proceed with caution if you need to start the instance during the period in which the data migration instance is paused. Otherwise, data inconsistency may occur.

   • If the migration instance does not have an Incremental Data Migration stage, skip this step.

   1. Wait until the latency of the migration instance is 0 milliseconds.

      Note

      • If the Auto Refresh feature is disabled, click the icon above the Actions column on the right to refresh the latency displayed on the page.

      • A latency of 0 may be a state for a short period.

      At this point, the data to be migrated from the source database is successfully migrated to the destination database.

   2. Continue to wait for 1 to 3 minutes.

      During this period, the latency of the instance may fluctuate within 2 seconds.

   3. On the Data Synchronization page, find the data synchronization instance that you want to pause and choose > Pause Task in the Actions column.

   4. In the message that appears, click OK.

   5. Wait until the Status of the instance changes to Paused.

5. Create a data migration task in the opposite direction.

   1. Keep your business suspended.

   2. Remove the limit on writing data to the source database.

   3. Create and start a data migration task in the opposite direction.

      Important

      • When you configure this instance, select only Incremental Data Migration for Migration Types.

      • For more information, see Overview of data migration scenarios.

   4. Wait until the Status of the instance changes to Running.

6. Switch workloads to the destination database

   1. Switch workloads to the destination database.

   2. Resume data write operations.

   3. Test whether your instance runs as expected.

Rollback solution

1. Suspend your business and stop writing data to the database.

2. Switch workloads back to the source database.

3. Resume data write operations.

What to do next

After you switch workloads to the destination database and test all the business-related features, you can stop the task in the opposite direction. For more information, see Stop a data migration task.