Google Apps Migration for Microsoft® Exchange is run on one or more client machines in your network, with a single instance of the utility on each client. If you run more than one instance of the utility, then those multiple instances run in parallel. Each instance of the utility migrates a specific list of users. The utility is multi threaded, with a thread opened for each user that’s being migrated. You can specify the number of users that are migrated simultaneously by an instance of the utility.
The following diagram illustrates how Google Apps Migration for Microsoft users’ data and migrates it to Google Apps.
Microsoft® Exchange Server
Google Apps Migration for Microsoft® Exchange
List of Users to Migrate
The utility reads the list of users you want to migrate. This is a list of users you create beforehand.
You can specify how many threads are processed simultaneously. For example, if you configure the utility to process 25 users at a time, and you have 25 users to process, 25 threads are spawned; however, if you have only 10 users to process in this case, only 10 threads are spawned. As soon as a thread finishes processing a user, it moves to the next user available in the list you submit.
Using the information you provide in the migration wizard, the utility opens the message store or PST file for each user identified in the list.
The utility retrieves mail data for each user. For Microsoft® Exchange, the utility can also retrieve calendar and contact data. Newer messages are migrated first.
The utility transforms email data to MIME. If you are migrating from Microsoft Server or PST files, this step uses Microsoft Outlook® components.
Google Apps Migration for Microsoft
Exchange Administration Guide