We are migrating to a new Exchange server that we have deployed in the same AD Forest as our older Exchange server. When I go thru the wizard I select the option that this is a “same forest migration”, but when I get to the page about matching accounts, the Auto-Match option doesn’t work??? Why do I have to create accounts, especially since the user accounts already exist???
In a same forest migration, there is no need to match to anything because there is only one directory (AD). However, the wizard is not very intuitive at this point for same-forest migrations. It is necessary at this wizard page to create new accounts…but some explanation may be helpful and may alleviate any concerns about this task.
In a same-forest migration the Priasoft migration process is as follows:
- Create a new user account in an OU
- This will be called the backup-user or placeholder account
- This account is hidden in the GAL
- It cannot be logged on to
- It cannot receive or send mail
- It will not conflict with any existing objects by name, logon name, email address, or any other attribute
- Mailbox-enable the backup account
- Migrate mail from the “real” user’s mailbox to the mailbox on the backup account
- On success, we will swap the critical identifiers between the 2 accounts, such that the “real” user will get the mailbox attributes from the backup user, and the backup user will get the mailbox attributes from the “real” user.
- Note that this “swapping” operation takes a mere second or two to perform in Active Directory, but Exchange will not recognize the swap for 5 or more minutes.
- If an attempt is made to logon to the mailbox immediately after the migration of it competes, the logon will still show the older mailbox.
This process model is used to ensure that we can provide a rollback if issues are found. It also provides a rollback option if there were no issues during migration, but sometime afterwards a rollback is needed.
This model is also used to support Priasoft’s 2-pass option, where a set number of days of regular mail is migrated in the “cutover” pass, and the balance of mail data is migrated in a “backfill” pass.
The backup account preserves the existence of the mailbox in the source exchange server, preventing it from being purged or deleted until you are ready (by simply deleting the backup user account).
Therefore, on the wizard screen “Matching” page, the only option is to Create, which will create the backup user accounts in some OU that you specify.
