In this phase, existing mail accounts and messages are migrated from the existing messaging environment to the Microsoft Exchange 2003 environment. Your migration strategy must be executed in a manner that is transparent and that has the minimum possible impact on your current e-mail users. To accomplish these goals, an effective migration strategy and appropriate migration tools must be designed and implemented. They must address all aspects of system migration, including networking, external interfaces, account synchronization, management systems, and parallel operations. This chapter contains the following sections: Developing a Migration Strategy, Preparing the Migration Plan, Using Migration Utilities, Tips for a Successful Migration. Refer to the Microsoft Exchange 2003 Migration Guide for complete information on migration.Checkout Migrate email using the Exchange cutover method for more info.
Developing a Migration Strategy
The typical site where Microsoft Exchange 2003 is installed has an existing mail system that provides messaging services to its users. Migration is the act of moving or copying the data for all users from the legacy (existing) system to the Microsoft Exchange 2003 system. Migration is performed so that all customers can be serviced by the Microsoft Exchange 2003 system, not simply those new subscribers following the installation of Microsoft Exchange 2003.
Migration is the most complex facet of any deployment project. Even though this document provides a framework to follow for migration, no two migrations are exactly alike, due to the differences in each site’s legacy mail system and its integrated systems and procedures. A successful migration depends upon accurately identifying all unique aspects of the system that are to be duplicated in Microsoft Exchange and then duplicating these conditions through development and testing prior to the actual physical migration.
The principal issues of concern in any migration to a new mail service are data integrity and transparent cutover to production. Data integrity guarantees that all mail accounts, stored messages, and associated personal information and preferences (for example, address books, passwords, and so forth) are accurately retained in the new mail system. Transparent cutover to production means that the transition is handled quickly, cleanly, and with no disruption to the end-user experience.
In typical migrations, the total amount of time required for a successful transition is a function of system complexity. Both the total number of mail accounts and the total number of stored messages are significant factors. In addition, migration time can be affected by system and site-specific issues.
Any migration strategy must address:
This migration involves all of the information that uniquely identifies and describes a user, including class-of-service data that defines the service for which users are subscribed. Account data must be placed in the Microsoft Exchange 2003 system before message data. The first task is therefore to collect and transfer account data from the legacy system and then transfer it to the Microsoft Exchange 2003 system. If your legacy system has domains and organizational units, you must prepare to migrate these also.
This migration involves message data–the actual messages to be migrated that belong to the user. The mailbox is simply a collection of the messages belonging to a particular account.
Preparing the Migration Plan
Migration involves significant planning, more so than any other deployment task. This planning is necessary because the activity is exposed to existing users and will, in most cases, be the initial experience that users have of the new system. It is very important to plan for every eventuality in order to avoid problems during the migration.