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Migration Execution

Refer to the following sections to execute the migration.

1. Configure projects and mappings in Fly

To configure projects and mappings, refer to the and for details. Use the mapping file of data to be migrated to configure the migration project.

2. Perform regular full migrations

Before running the job, we recommend you verify the mappings to ensure that the mappings are available for migration. Refer to for details.

Then you can run a full migration job to migrate the objects based on your configured migration policy. Refer to for details.

3. Perform regular incremental migrations

Some issues may occur during a full migration job. Run an incremental job to handle new, updated, and failed data. Refer to about how to perform regular incremental migrations.

4. Communicate with end users (optional)

Notify end users of the migration schedule. Publish a message in each source Group to inform end users that they can run incremental jobs before final validation.

5. Perform the final incremental migration and migrate membership

Notify all users and make sure the source Groups do not have any new/modified objects. Then perform the final incremental migration job.

After you complete your migrations, if the source membership is not included in the migrations, to make the destination Group available for users, run a Migrate membership job to only migrate the source membership, including owners, members, and guests. Refer to the section for details.

6. Compare the source and destination storage (optional)

After the migration, you can compare the number and size of files in the source and destination team sites by accessing the following URL:

sitecollectionurl/_layouts/15/storman.aspx

- If the number of files is different after the migration, check if the files that are not in the destination are migrated. If the files have not been migrated, check the comments of error files. After you fix the errors, rerun the migration job. If there are no records for these files, contact Support and provide the screenshots of these files and job ID to analyze the error.

- If the size of files is different after the migration, for example, the source file size is 10 MB, but the migrated file size is 100 MB, check the actual size of the source and migrated files in the source and destination libraries. Then, refer to the following instructions to resolve this issue:

	- If the actual size of the source file is 10 MB, the actual size of the migrated file is 10 MB, but the migrated file size displayed in the destination **Storage Metrics** page is 100 MB, it may be an issue of Microsoft.

	- If the actual size of the source file is 100 MB, the actual size of the migrated file is 100 MB, but the source file size displayed in the **Storage Metrics** page is 10 MB, it may be an issue of Microsoft.

	- If the actual size of the source file is 10 MB but the actual size of the migrated file is 100 MB, it is an issue of Fly. Contact Support and provide the screenshots of version histories of the source and migrated files, and screenshots of the **Storage Metrics** pages of the source and destination by accessing the following URL to analyze the error:

		sitecollectionurl/_layouts/15/storman.aspx

7. Validate migration results

Note the following items during the validation period:

- Number of files

- Number of mails in Group mailbox

- Number of planners and tasks

- No failed data in job report

8. Perform migrations for all other waves (optional)

This step is needed only if you have separated the mappings into multiple waves.

9. Perform the final incremental migration for other waves (optional)

You can perform the final incremental migration to make sure all source data are migrated to the destination if needed.

10. Perform the final validation

During the final validation, you should validate members of destination Groups.

11. Change domain

After you finish your migrations for the current wave, if you need to keep the source domain to the destination, you can change the domains of your source and destination environments.

Refer to the following steps for details:

Remove the domain from the source tenant.
To remove a domain from a Microsoft 365 tenant, refer to the .
Add the domain to the destination tenant.

To add a domain to a Microsoft 365 tenant, refer to the .
Add the new destination email address as an alias of the destination user and set the new email address as the primary email. This ensures the destination users can use the new email addresses.
Then, if you want to perform a final incremental migration to migrate the new or modified data to the destination, you must update the domain names of source and destination Group email addresses in Fly first. Refer to the user guide for for details.

Preparation