Create a sharding users list (Optional)

To migrate a large number of files (more than 400,000) to Google Drive from file shares, create a sharding users list. Use a sharding users list even if you intend to migrate the content to multiple shared drives. It's important to ensure that a large volume of content is spread across many creator accounts regardless of how many shared drives you intend to migrate to.

If you're migrating fewer than 400,000 files to a single user’s Drive account, you should skip this step. Go to Create a scoped view.

What is a sharding users list?

A sharding users list is a CSV file with email addresses from your target account. The user accounts belonging to the email addresses are used to write objects to a user's My Drive or a shared drive.

Spreading the migration load across a larger group of users helps avoid API bottlenecks and congesting the Drive service.

Understand permissions and ownership


No additional users, including the sharding users, receive elevated access to file content during the migration process.

A migration to My Drive does not affect access control lists (ACLs) and ownership of files and folders. Files you migrate to shared drives are subject to the access level set by the administrator. For details, see Control access to files in shared drives.

File creators and modifiers

The file modifier metadata is preserved in migrated data. Each file’s version history shows the correct modifier.

If you are migrating to shared drives, the sharding user is displayed as the file creator. You can’t change this attribute. To see this information in the shared drive, click the fileand thenInfo . The username of the creator is also shown in the Drive audit log next to Create or Upload events. For details, go to Drive audit log.

Stub files

During the migration, you might see stub files with arbitrary names in Drive. These files are placeholders for the actual file and have no data. In the audit log, the sharding user is shown as the owner of the stub file. 

Stubbed file versions aren’t recorded in the version history. Shortly after the stub file creation, the actual file migrates. The expected user (as specified in the identity mapping) appears as the file owner in the log. 

Temporary folders

Some temporary folders are created during a migration in the sharding user’s My Drive and are usually automatically deleted. Under particularly heavy API load, some might remain after a migration. You can safely delete those folders.

Step 1: Create temporary users (recommended)

You can see the user accounts in your sharding users list in the Drive audit log for the migrated files. For example, you can see which user account created a file. To avoid any confusion with active users, we recommend that you set up temporary Google Workspace users using an easily identifiable username, such as shard-user1. Use the new accounts for your sharding users list. Then, delete the users after you complete the migration.

To determine the number of user accounts to add to the sharding users list, compare the following 2 options and use the larger value:

  • One account per 400,000 files that are being migrated to Drive
  • 10 accounts per node

For details on adding and deleting users, see Options for adding users and Delete a user from your organization.

Afterward, make sure the temporary users:

  • Have a license for the migration period. The license must match the highest version of the Google Workspace edition that you’ve assigned to your target domain. Learn more
  • Are able to access the Google Workspace services you're migrating to, for example, Gmail and Drive. Learn more
  • Can access Drive files using the Drive API. Learn more

Step 2: Create the CSV file

Create the list in a spreadsheet program with one entry per line:

  • Headers are not required.
  • Save the spreadsheet as a CSV file.
  • Make sure the character encoding of the CSV file is set to UTF-8. 

Sharding user list CSV file

Step 3: Add the list

In the Google Workspace Migrate platform, click New and thenList.

  1. Enter a name for the list.
  2. Under Type, click the Down arrow and thenUsers.
  3. Click Upload CSV file to upload a CSV file or drag a file to the box.
  4. Click Create.

You'll be able to select the list when creating a bridge.

Related topics

Next step

Create a scoped view

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