Applies to: Exchange Server 2007 SP1, Exchange Server 2007 Topic Last Modified: 2008-03-24

The Microsoft Exchange Server 2007 database portability feature allows a mailbox database to be mounted on any server in the same organization. In previous versions of Exchange, a database could only be mounted in the following places:

• Recovery storage group
  
• Server with the same name as the server that the database came from
  
• Another server in the same administrative group
  

  Note:
  In Exchange Server 2003 and Exchange 2000 Server, several issues needed to be addressed when moving a database to another server in the same administrative group.

The database portability feature removes the previous limitations and handles the issues that they presented. Database portability was implemented for the following reasons:

• Reliability is improved by removing error-prone manual steps in the recovery processes.
  
• For a lost clustered mailbox server scenario, the clustered mailbox server needed to be recovered before clients could access Exchange databases.
  
• Exchange mailbox data is non-server specific, so accessing that data should also be non-server specific.
  
• Database portability reduces the end-to-end recovery times for various disaster recovery scenarios.
  

At the Extensible Storage Engine (ESE) level, Exchange databases are portable. However, Exchange Server 2003 imposes certain restrictions before bringing a database online at an alternate location that do not allow databases to be portable. Database portability removes all but one such restriction, which is that the database needs to be from the same Exchange organization. A portable database is of no use, unless clients can be redirected to the mailbox data at the alternate location. With the Microsoft Office Outlook 2007 and the Exchange 2007 Autodiscover service, clients are redirected to the new server when they try to connect.

Note:

Database portability is only offered for Exchange 2007 mailbox databases. Public folder databases are not portable. This is because replication between public databases is controlled by each database being linked to and accessed through a specific server. The preferred way to move public folder data between servers is to replicate it rather than copy the database files to a different server. If you copy a public folder database to a different server, it will no longer replicate with other databases.

For information about how to perform a database recovery using the database portability feature, see How to Restore a Mailbox Database to a New Server with Database Portability.

 Using Database Portability Across Operating Systems or Exchange Versions

Mailbox databases from previous versions of Microsoft Exchange cannot be moved to a mailbox server running Exchange 2007. Database portability is for Exchange 2007 mailbox databases only.

Database Portability Between Exchange RTM and SP1

Using database portability, you can move a mailbox database from a server running the release to manufacturing (RTM) version of Exchange Server 2007 to a server running Exchange Server 2007 Service Pack 1 (SP1); however, you cannot use database portability (or any other means) to move a database from Exchange 2007 SP1 to Exchange 2007 RTM. Table 1 illustrates the supported uses of database portability.

Table 1   Compatibility matrix for database portability

Source mailbox server	Supported target mailbox servers
Exchange 2007 RTM on Windows Server 2003	Exchange 2007 RTM on Windows Server 2003 Exchange 2007 SP1 on Windows Server 2003 Exchange 2007 SP1 on Windows Server 2008
Exchange 2007 SP1 on Windows Server 2003	Exchange 2007 SP1 on Windows Server 2003 Exchange 2007 SP1 on Windows Server 2008
Exchange 2007 SP1 on Windows Server 2008	Exchange 2007 SP1 on Windows Server 2008

Database Portability Across Windows Server Versions

As with previous versions of Microsoft Exchange, an upgrade of the operating system for an Exchange server results in the updating of the value for OS Version in the database header. This update triggers the rebuilding of internal database indexes. When using database portability to move a database from a Mailbox server running Windows Server 2003 to a Mailbox server running Windows Server 2008, the Extensible Storage Engine (ESE) detects the operating system upgrade and takes the following actions:

• During the first database mount operation, all secondary indexes are discarded. A secondary index is used to provide a specific view of the mailbox data (for example, when messages in a mail folder are sorted using Outlook in Online mode). The database will not be mounted and available to clients until this initial operation is complete. The amount of time to complete the operation is largely dependent on the size of the database. The larger the database is, the longer the mount operation will take.
  
• Secondary indexes will be rebuilt on-demand as Outlook users sort their views in Online mode. In environments with large or extremely large databases, the on-demand rebuilding of indexes will initially result in high processor and disk utilization.
  

While index rebuilding is occurring, ESE will log the following event in the Application event log:

Event Type: Information Event Source: ESE Event Category: Table/Column/Index Definition Event ID: 611 Description: MSExchangeIS (6568) <ServerName>_<StorageGroupName>: Database '<PathtoDatabaseFile>': The secondary index '<Index GUID>' will be rebuilt as a precautionary measure after the Windows version upgrade of this system. This message is informational and does not indicate a problem in the database.