Introduction Currently, Microsoft support policy does not apply to the database mirroring feature in Microsoft SQL Server 2005.
By default, database mirroring is disabled. However, you can enable database mirroring for evaluation purposes simply by using trace flag 1400 as a startup parameter. Database mirroring should not be used in production environments. Microsoft Product Support Services does not support databases or applications that use database mirroring. The database mirroring documentation included with SQL Server 2005 is for evaluation purposes only. Additionally, SQL Server 2005 support and upgraded document policies do not apply to database mirroring documents.
After you start your SQL Server 2005 instance with trace flag 1400, you can set up and evaluate database mirroring. For more information, see SQL Server 2005 Books Online.
NOTE: Trace flag 1400 is a temporary flag. Trace flag 1400 will be removed when the database mirror is available for regular production.
MORE INFORMATION Consider the following questions when using database mirroring with SQL Server 2005.
Preparing to upgrade to SQL Server 2005 Final version Set the recovery queue size to UNLIMITED before upgrading
In the final version of SQL Server 2005, the UNLIMITED value is the only supported recovery queue size. Additionally, the SET PARTNER REDO_QUEUE option of the ALTER DATABASE statement is not supported. To avoid future problems with database mirroring, you must reset any inconsistent database sizes to UNLIMITED values before upgrading.
To view the database recovery queue settings for a SQL Server instance, see the mirroring_redo_queue_type column in the sys.database_mirroring catalog view. The only value supported by the mirror database is UNLIMITED. If the database value is MB, execute the following Transact-SQL statement against the database on the current principal server. ALTER DATABASE <database_name> SET PARTNER REDO_QUEUE UNLIMITED
Pause or stop database mirroring before upgrading either partner If one partner is running the final version of SQL Server 2005 and the other partner is running a pre-release version of SQL Server 2005, database mirroring will not run. Database mirroring should be paused or stopped for all database mirroring sessions before upgrading either partner. Then, upgrade all partners and restore database mirroring.
Setting up and evaluating database mirroring does not support the SET PARTNER REDO_QUEUE option of the ALTER DATABASE statement. The UNLIMITED value is the only supported recovery queue size.
Handling Problems with the Log Drive on the Principal Server If there is a problem with the log drive on the principal server, log records that have been sent to the mirror server and that are replayed on the mirror database may never be written to the principal server's disk. In this case, the log backup created here cannot be applied to the mirror database. Therefore, please ensure that the database mirroring session continues to run. As long as the database mirroring session is running normally, you can fix the problem with the log drive or switch partner roles. You can switch partner roles through database mirroring failover and resynchronization or by forcing services to a mirrored database. If you force service a mirror database, any new log records that have not yet reached the mirror server will be lost.
Important: Keep database mirroring running. If you turn off database mirroring, you must perform a full backup and restore the database to rebuild database mirroring.