1. Make sure that the two partners that is the principal server and mirror server, are running the same edition of Microsoft SQL Server 2005. The partners require either SQL Server 2005 Standard Edition or SQL Server 2005 Enterprise Edition or SQL Server 2005 Developer Edition.
2. If you are using a witness, make sure that SQL Server 2005 is installed on its system. The witness can run on any reliable computer system that supports SQL Server 2005 Standard Edition, Enterprise Edition, Workgroup Edition, or Express Edition.
3. SQL 2005 SP1 or later version is required for Mirroring
4. The principal database must be in the FULL recovery model. Log records that result from bulk-logged operations cannot be sent to the mirror database.
5. Verify that the mirror server has enough disk space for the mirror database.
6. All of the server instances in a mirroring session should use the same master code page and collation. Differences can cause a problem during mirroring setup.
7. The mirror database must have the same name as the principal database.
8. The mirror database must be initialized from a restore of the principal database with NORECOVERY, followed by restores in sequence of principal transaction log backups. Prior to configuring mirroring ensure that at least 1 tran log is restored in addition to full backup with NORECOVERY mode.