Applies to: Exchange Server 2007 SP3, Exchange Server 2007 SP2, Exchange Server 2007 SP1, Exchange Server 2007
Topic Last Modified: 2007-09-05

This section provides procedures related to recovering a failed database by performing a dial tone recovery on servers running Microsoft Exchange Server 2007. A dial tone recovery involves creating an empty database on a server to replace a failed database. This empty, or dial tone, database allows users to send and receive e-mail while the failed database is recovered. By using a dial tone recovery approach, you can restore basic e-mail service to users (providing them with a "dial tone") and then restore users' previous data as it becomes available.

This section provides information about several methods of performing a dial tone recovery:

• Dial tone recovery on the server with the failed database
  
  
• Dial tone recovery using an alternate server for the dial tone database
  
  
• Dial tone recovery using and staying on an alternate server for the dial tone database
  
  

All three methods use the following basic steps:

1. Create a new empty dial tone database to replace the failed database   This new database will allow users who had mailboxes on the failed database to send and receive new messages. Exchange 2007 has a feature called dial tone portability that allows you to point a user to a different database without moving the mailbox. If you created the dial tone database on a different server than the server that housed the failed database, you will need to move the mailbox configuration to that new server. For more information about the dial tone portability feature, see Dial Tone Portability.
   
   
2. Restore the old database   Use whatever backup and recovery software you typically use to restore the failed database. If there is no backup of the failed database, recover the failed database. If you are using the same server for dial tone recovery, you need to restore the database to a recovery storage group. For more information about recovery storage groups, see Understanding Recovery Storage Groups.
   
   
3. Swap the dial tone with the restored database   After the failed database has been restored, swap it with the dial tone database. This gives the users the ability to send and receive e-mail and access all the data in the restored database. If users were moved to a dial tone database on another server, you then need to move the mailbox configuration back to the original server.
   
   
4. Merge the databases   To get the data from the dial tone database into the restored database, merge the data. You can do this with the Database Recovery Management tool included in the Exchange Management Console. For more information about the Database Recovery Management tool, see Database Recovery Management and Database Troubleshooter Tools.
   
   

The methods have different advantages and disadvantages as follows:

• Recovery on the server with the failed database   If a database fails on an Exchange 2007 server and the server is still functional, it is a best practice to perform a dial tone recovery on the server that originally held the failed database. The reasons for this approach are as follows:
  
  
  • Your organization will have less downtime because you will not need to move databases and configure mailboxes between servers. You also do not need to reconfigure Outlook profiles.
    
    
  • There are fewer steps to this procedure, which make it less complex, with a smaller margin for error.
    
    
• Recovery using an alternate server for the dial tone database   If a server fails and needs to be rebuilt, the most efficient way to give users basic mail functionality is to quickly create a dial tone database on another server, and move the mailbox configuration to that new server. Keep in mind the following:
  
  
  • This process will require that you move the dial tone database back to the recovered server. This step adds more time to the overall recovery process.
    
    
  • This process is more complex than performing a dial tone recovery on a single server.
    
    
  • The server that you are temporally placing the dial tone database on might not have sufficient resources to support the added load of the additional users.
    
    
  • Without Office Outlook 2007, you might have to manually reconfigure users' Outlook profiles to point to the new Exchange server.
    
    
• Recovery using and staying on an alternate server for the dial tone database   Sometimes it isn't feasible to recover the failed server. In this case, it might be necessary to stay on an alternate server. If the server that you are using as your alternate server has sufficient resources and can handle the additional load, this might be a good opportunity to consolidate servers.
  
  

For More Information

To ensure that you are reading the most up-to-date information and to find additional Exchange Server 2007 documentation, visit the Exchange Server TechCenter.

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