Incremental server migration - Server Migration Center - Alibaba Cloud Documentation Center

Server Migration Center (SMC) allows you to migrate incremental data from source servers to Alibaba Cloud. You can specify the time interval between two consecutive incremental migration operations. Incremental migration reduces the service downtime and the total time of migration. This topic describes how to migrate incremental data from a source server.

Procedure

(Optional) Step 1: Filter the dynamic data directory

To ensure stable migration, we recommend that you exclude dynamic data directories, such as data directories of large databases, before you start an incremental migration job. Later, you can stop the services on the source server and migrate the excluded directories. Skip this step if you do not need to exclude dynamic data directories from migration.

To exclude dynamic data directories, perform the following steps. You do not need to stop the services that are running on the source server. For more information, see the How do I exclude files or directories from a migration job? section of the "FAQ" topic. in which the RDS instance resides.

Step 2: Create an incremental migration task

If the services of the source server are not suspended, you must import the migration source and create an incremental migration task. For more information about the operations in each migration scenario, see:

When you create a migration task, you must enable the Automatic Incremental Migration parameter in Expert Mode.

The following table describes the parameters that are related to automatic incremental migration.

Automatic Incremental Synchronization: Turn on this switch.
Synchronization Interval: the time interval between two consecutive incremental migration operations. Minimum value: 1 hour. Maximum value: 7 days.
Upperlimit of Reserved Images: the maximum number of reserved images. Valid values: 1 to 10. Each incremental migration generates a new image. When the total number of image files generated exceeds this value, the earliest and unused image files are deleted.

The incremental migration task immediately starts after it is created. The execution result is described as follows:

During the first incremental migration operation, SMC migrates all data except the excluded directories and files, and generates a full image. You can use this image to create an instance for verification.
After the first incremental migration operation is complete, SMC automatically migrates incremental data and generates images at specific points in time based on the synchronization interval.
Note
The image generated for each incremental migration operation is a full image of the source server at a specific point in time. The image includes the incremental data at the point in time of migration and all earlier migrated data.

Step 3: Suspend the service and run incremental data migration

During off-peak hours, after the services of the source server system are suspended, release the previously filtered data directories and run incremental migration again. To create a workflow, perform the following steps:

Log on to the source server, suspend system services, and release the data directory that is filtered out in Step 1.
In the SMC console, manually run the incremental migration task or wait for the task to automatically run.
Note
Automatic execution is executed based on the gap set by the Synchronization Repeat Frequency parameter that you configure.
To manually run the incremental migration task, perform the following steps:
1. In the Actions column of the migration source, click Manually Synchronize Incremental Data.
2. In the Manual Incremental Synchronization message, click OK.
  Note
  - To pause the incremental migration task, choose > Pause Task under Actions for the migration source.
  - To delete the incremental migration task, choose > Delete in the Actions section of the Migration Source page and follow the instructions to delete the incremental migration task.
3. View the incremental data synchronization result.
  If the migration progress is 100%, incremental synchronization is complete.

Step 4: Complete incremental synchronization

After the last incremental data synchronization task is completed, incremental data synchronization is completed.

Find the migration source and click Complete Incremental Synchronization in the Actions column.
In the Run Incremental Job dialog box, click OK.
You can also select Last Synchronization in the Complete Incremental Task dialog box to complete the last data synchronization.
On the Migration Tasks page, view the real-time migration status.
The time required to transfer data is affected by factors such as the source data size and network bandwidth. Wait until the migration task is complete.

Verify the migration results

If Migration Status is Completed, the migration is successful.
You will get the data at the final point in time, including all the data of the first full migration of the source server system and each subsequent incremental migration.
- If you set Destination Type to ECS Image,
  Manually verify migration results (recommend)
  You can click Create Instance in the Actions column to go to the Create ECS page in the ECS console. The custom image is selected by default. For more information about how to create an ECS instance, see Create an instance from a custom image.
  Automatically verify migration results
  Note
  To use this feature, you must install the Cloud Assistant plug-in in the instance. The system version of the instance supports this feature. For more information, see Install the Cloud Assistant Agent.
  This feature uses the OOS template ACS-SMC-CreateAndVerifyInstance provided by Alibaba Cloud to automatically verify whether the image generated by the migration task can successfully create an ECS instance and start it normally.
  Click Verify Migration Result in the Actions column.
  In the dialog box that appears, read the instructions on the verification process and click Verify Now.
  You can also click Customize Verification Parameters to configure the parameters.
  In the Verify Migration Result column, view the verification result.
  Verified: indicates that the migration is successful. You can click Show Output Parameters to check the details.
  Not Verified: indicates that the migration failed. You can click View Cause to view the cause of the migration task and troubleshoot the issue based on the cause.
  You can also click the icon in the Actions column and select View Verification Records in OOS Console to view the template history.
- If you set Target Type to ECS Instance, click View Target Instance in the Actions column to go to the Target Instance page and view the target ECS instance.
After the server is migrated, you need to perform the following operations to ensure the normal operation of your business:
- Verify and verify the data to ensure the integrity and correctness of the data. For more information, see the How do I check my system after I migrate a Linux server? or How do I check my system after I migrate a Windows server? section of the "FAQ" topic. in which the RDS instance resides.
- If applications and services on the source server are not automatically started, you must manually start the applications and services after the migration.
- The IP address will change after the migration. If the service involves the configuration of IP addresses, modify the configuration.
  If a domain name has been bound to the source server, the public IP address of the source server will change after the migration. You must resolve the domain name to the new public IP address of the source server. For more information, see Add a website.
  If you want to keep the private IP address unchanged, you can modify the private IP address after the migration is complete. For more information, see Modify the private IP address of an instance.
If Migration Status is Drill Exception, the migration drill fails.
You need to view the drill report and fix the serious drill items, and then retry the migration drill. For more information, see Configure a migration test.
If Migration Status is Error, the migration task fails.
In this case, you need to troubleshoot the issue and try again:
1. In the Actions column, click Troubleshoot Errors and fix the error based on the error code and error message. For more information, see FAQ and Errors occurred during a server migration.
2. On the Migration Tasks page, click Retry Task.
  The migration task continues at the last completed progress.
  Important
  If the intermediate instance is released, you must create another migration job. For more information, see the What do I do if I release an intermediate instance by accident? section of the "FAQ" topic.

Clean up resources

Migrate images to ECS instances
During migration, SMC creates a temporary pay-as-you-go intermediate instance named No_Delete_SMC_Transition_Instance under your Alibaba Cloud account to assist in the migration. You need to select whether manual cleanup is required based on whether the migration is successful:
- If the migration is successful, the intermediate instance is automatically released. You do not need to manually clean it up.
- Migration error: The intermediate instance always exists with the migration task and costs are incurred. You can choose one of the following methods to release the intermediate instance to avoid unnecessary fee deduction:
  - If you no longer want to use the migration task, choose > Delete in the Actions column to delete the migration task.
  - Manually release the intermediate instance. For more information, see Release an instance.
Migrate data to the destination instance
During migration, SMC creates a temporary pay-as-you-go intermediate disk named SMC_Temp_Disk in the destination instance to assist in the migration. You need to select whether to manually clean the intermediate disk based on whether the migration is successful:
- Successful migration: The intermediate disk is automatically released. You do not need to manually clean it up.
- Migration error: The intermediate disk persists with the migration task and generates fees. You can choose one of the following methods to release the intermediate disk to avoid unnecessary fee deduction:
  - If you no longer want to use the migration task, choose > Delete in the Actions column to delete the migration task.
  - Manually release the intermediate instance. For more information, see Release a disk.