When performing a G Suite to G Suite migration and only a subset of the total source user base is migrating, there are special considerations when migrating Google Drive. CloudMigrator has configuration options that can be used depending on the migration scenario. There are two general use cases to consider:
(1) Maintaining source permissions for the non-migrating users, if you require non-migrating user's permissions to be maintained in the destination
(2) Not maintaining or replacing the source permissions, if you do not wish to maintain non-migrating user permissions
Guide to maintaining source permissions for the non-migrating users during migration
(1) Per our documentation, the general guidance should always be followed. Primarily, you should always provision all of your users and groups before performing a Google Drive to Google Drive migration. This is required to ensure all sharing and Drive hierarchies are preserved correctly during the migration. In this use case, however, the following applies:
(a) Ensure that all migrating users exist in the destination
(b) Ensure that all groups and members are created or are mapped in the destination, also.
(2) Configure an Address Replacements CSV per this article, replacing the migrating users (and any aliases), all groups and the migration domains like this basic example:
(3) Enable 'Address Replacements' / 'Replace CSV Addresses Only'.
(4) Enable 'Migrate Items Only From Listed Users' in the source G Suite settings.
(5) In Users, Get Users and then remove the non-migrating users, or import a CSV list of all migrating users.
Migrating a subset of users without maintaining the source permissions
If you do not wish to maintain permissions for users who are not migrating, prepare and configure the migration as per this guide, creating all migrating users and groups, using the default CloudMigrator settings for Drive and list only migrating users in the user list and Address Replacements. When migrating Drive, any folders owned by non-migrating users will be migrated. Ownership will be changed to the migrating user and any explicit file and folder permissions will attempt to be replaced because the destination address does not exist. All migrating user permissions will be applied.
If migrating into a G Suite domain with existing users, conflicting addresses should be considered. If users exist at the destination domain with prefixes of existing source users, the replacements may cause items to be shared with those users. To avoid this, enable "Replace CSV Addresses Only" and list only ALL migrating users in the Address Replacements (File).
Drive Readiness is highly recommended. The Drive Readiness Test inspects your domains, users, groups, the user list, address replacements and your configuration settings and highlights any potential issues with the configuration. You should run a Drive Readiness Test before performing a Google Drive to Drive migration to ensure you achieve the desired results.