Migrate incremental data from a server - Server Migration Center

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

Procedure

Step 1: Perform the full migration

After you import the information about a migration source, perform migration configuration. You do not need to stop the services that are running on the source server. For more information about the operations for different migration scenarios, see the following topics:
When you perform the migration configuration, turn on Automatic Incremental Synchronization. Configure the following parameters related to automatic incremental migration:
- Automatic Incremental Synchronization: specifies whether to enable automatic incremental migration. Turn on this switch.
- Synchronization Interval: the time interval between two consecutive incremental migration operations. For example, if Synchronization Interval is set to 1 hour, the next incremental synchronization will start 1 hour after the completion of the current incremental synchronization. You can specify a time interval in the range of one hour to seven days.
- Maximum Reserved Images: the maximum number of images that can be retained during incremental migration. Valid values: 1 to 10. An image is generated for each incremental migration operation. If the total number of images exceeds the upper limit, the earliest unused image is deleted.

View the migration results.
If the migration progress is 100%, the first full migration is completed and a full image is generated. Each time the migration is completed, the real-time status of the migration is Waiting to wait for the arrival of the next frequency cycle and continue to migrate incremental data.
Note
You can perform the following operations based on your business requirements:
- Verify the migration result: You can click > Create an instance in the Actions column of the migration source, and use this image to create an Elastic Compute Service (ECS) instance for verification.
- Modify the synchronization interval: You can click > Automatic Incremental Synchronization in the Actions column of the migration source to modify the synchronization interval as prompted. The modification will take effect after the next incremental synchronization ends, not immediately.
- Stop the migration task: You can click > Pause Migration Job in the Actions column of the migration source to stop the migration task as prompted.
- Cancel the incremental migration task: You can click > Cancel Migration in the Actions column of the migration source to cancel the incremental migration task as prompted.

Step 2: Stop the services on the source server and run an incremental migration task

Stop the services on the source server during off-peak hours, and then run the incremental migration job again.

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 contains the incremental data at the point in time of migration and all earlier migrated data.
After automatic incremental synchronization or manual incremental synchronization starts, data comparison is performed firstly. The data comparison speed is related to the disk I/O capacity and is not limited to the network bandwidth. Therefore, the comparison time is affected by the disk I/O capacity and the amount of disk data. After the data comparison is completed, the incremental data is transmitted, and the time spent in the incremental data transmission phase is affected by the incremental data size and network bandwidth. For more information, see Estimate the time required for migration and test the data transfer speed.

Log on to the source server and stop the services on the source server.
In the SMC console, manually run the incremental migration job or wait for the job to automatically run.
- Perform incremental migration automatically.
  After the first incremental migration is completed, SMC automatically performs the incremental migration and generates a new image at the corresponding time point based on the value of Synchronization Interval that you set.
- Perform incremental migration manually.
  In the Actions column of the destination migration source, click Manual Incremental Synchronization. In the displayed dialog box, click OK.

Step 3: Complete incremental migration

After the last incremental migration operation is complete, perform the following steps to complete incremental migration.

On the OS Migration page, find the migration job that you want to manage and click Complete Incremental Synchronization in the Actions column.
In the Run Incremental Job dialog box, click OK.
You can also select Perform One Last Synchronization in the Run Incremental Job dialog box to perform the last incremental migration operation.
On the Server Migration page, view the status of the created job.
The amount of time required for data transmission is subject to factors such as the data size of the migration source and network bandwidth. Wait until the migration job is complete.

Important

After you complete incremental migration, no more incremental migration operations are automatically performed and you cannot manually run the migration job. If you click Complete Incremental Synchronization and confirm the completion by accident but still need to migrate incremental data, you can create an incremental migration job again.

Verify the migration result

If the migration job enters the Completed state, the migration is successful.
You can obtain the data that is generated for the last migration operation. The data contains all the data migrated by the first full migration operation and each subsequent incremental migration operation.
- If you set the Destination Type parameter to ECS Image for the migration job, you can verify the migration result in the following way:
  (Recommended) Manually verify the migration result
  You can click Create Instance in the Actions column to go to the ECS instance creation page in the ECS console. The custom ECS image created by the migration job is selected by default for you to create an ECS instance. For more information, see Create an instance by using a custom image.
  Use the automatic migration result verification feature
  Note
  To use this feature, you must install the Cloud Assistant Agent in your instance, and the system version of the instance must support this feature. For more information, see Install Cloud Assistant Agent.
  This feature uses the ACS-SMC-CreateAndVerifyInstance template provided by Alibaba Cloud CloudOps Orchestration Service (OOS) to automatically verify whether the image generated by the migration job can be used to create an ECS instance and whether the ECS instance can start as expected.
  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. Valid values:
  Verified: indicates that the migration is successful. You can click Details to check the verification result.
  Not Verified: indicates that the migration failed. You can click View Cause to troubleshoot the failure.
  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 the Destination Type parameter to ECS Instance for the migration job, you can click View Destination Instance in the Actions column to go to the details page of the destination ECS instance to verify the migration result.
After the server is migrated, you must perform the following operations to ensure normal operation of your business:
- Verify 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.
- Manually start the applications and services after the migration if automatic start is not enabled for the applications and services on the source server.
- The IP address changes after the migration job is complete. If the service involves the configuration of the IP address, modify the domain name resolution and ICP filing after the migration.
  If a domain name has been bound to the source server, the public IP address of the server is changed after the migration. In this case, you must resolve the domain name to the new public IP address of the server. For more information, see Add website resolution.
  If you want to keep the private IP address unchanged, you can modify the private IP address after the migration is complete.
  Migrate a server to an ECS Image: Modify the private IP address when creating an ECS instance. For more information, see Specify the primary private IPv4 address when creating an ECS instance.
  Migrate a server to a Destination Instance: If you have not modified the IPv4 private network address in the advanced configuration of the Migration Settings step, you can also modify the IPv4 private network address after migration. For more information, see Change the primary private IPv4 address for an existing ECS instance.
The migration test failed if the migration job enters the Drill Exception state.
In this case, you need to check the test report, fix the test items that are in the Critical state, and then perform a test again. For more information, see Configure a migration test.
If Error is displayed in the Real-time Migration Status column, the migration failed.
In this case, you need to perform the following operations:
1. Click Troubleshoot Errors in the Actions column and fix issues based on the error code and description. For more information, see FAQ about Server Migration Center (SMC) and Errors occurred during a server migration.
2. After the issues are fixed, click Retry Migration in the Actions column of the migration job.
  The migration job resumes from the point where it was suspended.
  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.

Clear resources

Migrate a server to an ECS image
During the migration, SMC creates a temporary pay-as-you-go intermediate instance named No_Delete_SMC_Transition_Instance within the destination Alibaba Cloud account. The method to clear resources depends on whether the migration is successful.
- If the migration is successful, the intermediate instance is automatically released. No manual operation is required.
- If the migration failed, the intermediate instance is not automatically released and incurs fees as long as the migration job exists. You can release the intermediate instance in one of the following ways to reduce costs:
  - If you no longer need the migration job, click the ID the migration job. On the job details page, click > Clear migration task in the Actions column in the Migration Jobs section to delete the migration job and release the intermediate instance at a time.
  - Manually release the intermediate instance. For more information, see Release an instance.
Migrate a server to an ECS instance
During the migration, SMC creates a temporary pay-as-you-go intermediate cloud disk named SMC_Temp_Disk in the destination instance. The method to clear resources depends on whether the migration is successful.
- If the migration is successful, the intermediate cloud disk is automatically released. No manual operation is required.
- If the migration failed, the intermediate cloud disk is not automatically released and incurs fees as long as the migration job exists. You can release the intermediate cloud disk in one of the following ways to reduce costs:
  - If you no longer need the migration job, click the ID of the migration job. On the job details page, click > Clear migration task in the Actions column in the Migration Jobs section to delete the migration job and release the intermediate cloud disk at a time.
  - Manually release the intermediate instance. For more information, see Release a disk.