Applies To: Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2
Applies to: Active Directory Migration Tool 3.2 (ADMT 3.2)
To protect your system against the problem of open sets when you restructure Active Directory domains within a forest, migrate groups before you migrate the user accounts that are members of those groups. If you migrate groups simultaneously with migrating users, you might not migrate nested groups, which creates an open set.
In addition, follow these guidelines for migrating groups:
Migrate universal groups first, followed by global groups.
Migrate domain local groups when you migrate the resources (domain controllers and member servers) on which they are used to assign permissions.
You can choose to migrate computer local groups when you migrate the computer later in the restructure process.