Google Apps Migration for Microsoft Exchange Administration Guide - Manual (Page 58)

58 Google Apps Migration with IMAP Connector Administration Guide
What to expect during migration
With Exchange, contacts are migrated first, followed by calendar data, and then email.
Your users can work with their Google Apps accounts during migration.
If a user in the list is not also provisioned in Google Apps, the migration moves on to the next
user. If the migration encounters a mail store it cannot open, it moves on to the next user in the
list. If the migration encounters an error with a particular item, for example a message, it
moves on to the next item.
Errors are recorded in the log files. You can find log files in the following location:
(for Win XP family)
C:\Documents and Settings\user-name\Local Settings\Application
Data\Google\Google Apps Migration\Tracing\ExchangeMigration
(for Vista/Win7 family)
C:\Users\user-name\AppData\Local\Google\Google Apps
Migration\Tracing\ExchangeMigration
user-name
in the path identifies the administrator who logged in and ran the utility.
For example:
ExchangeMigration.exe --nouse_gui --exchange_admin_login="Administrator" --
source_server="ExchangeServer" --google_domain="domain.com" --
filename="C:\pst\users.csv" --pst_base_folder="C:\pst" -
google_consumer_key="domain.com" --
google_consumer_secret="************************"
Best practices
Avoid remigrating contact and calendar data that you have already migrated.
If you remigrate contact data, you end up with duplicate contacts.
If you remigrate calendar data, you can encounter problems. For example, if you migrated a
recurring event, made a change to it in Google Apps, and then remigrated that same event,
the change you made in Google Apps would be lost.
If you need to remigrate contact and calendar data for some reason, you need to first delete
the data you migrated originally, and then run a new migration.
Migration Considerations
When planning your migration, take the following considerations into account.