Now that SQL Server 2005 is coming down the home stretch in preparation for its release on November 7, 2005 , it's time for its product team to start making the hard choices about what will be finished and included, and what will have to be rolled out in updates after the official release.
It looks like one of the casualties is Database Mirroring. This new high availability feature will be part of SQL Server 2005, but it won't be supported (it will officially be included as an "evaluation" feature), which means that Microsoft hasn't finished all of the work that it wants to do with this feature. Obviously, as a feature that IT departments will be depending on to reduce downtime, Database Mirroring has got to be perfect.
For the recond, Microsoft is saying that it simplying has not gotten enough real world testing done with Database Mirroring, and that's the reason for the delay. Paul Flessner, Microsoft's senior VP for server apps, has also said that Microsoft will make a full release of Database Mirroring in the first half of 2006.