Prerequisites for Database Mirroring

•  SQL Server 2005 with SP1 or SQL Server 2008 …
• The database must use the full recovery model. The simple and bulk-logged recovery models do not support database mirroring.
• Service Broker should be enabled on the database.
• Both servers should either Enterprise or Standard Editions or Developer.
• The two partners, that is the principal server and mirror server, must be running the same edition of SQL Server. The witness, if any, can run on any edition of SQL Server that supports database mirroring.
• Database name should be same.
• Verify that the mirror server has enough disk space for the mirror database.
• Collation should be same
•  When you are creating the mirror database on the mirror server, make sure that you restore the backup of the principal database specifying the same database name WITH NORECOVERY. Also, all log backups that were created after that backup was taken must also be applied, again WITH NORECOVERY.
• Only user databases can be mirrored. You cannot mirror the master, msdb, tempdb, or model databases.
• A mirrored database cannot be renamed during a database mirroring session.
• You can’t mirror more than 10 db in 32 bit server, because an instance can only have one end point which could be a bottle neck if there are lots of db’s in that instances.
• You can’t attach or detach.
• Mirroring Ports should be open and functional.
• Service Account should be same for SQL and SQL agent on Instance.
• For a mirroring session to be established, the partners and the witness, if any, must be running on the same version of SQL Server.
• Database mirroring does not support FILESTREAM. A FILESTREAM filegroup cannot be created on the principal server. Database mirroring cannot be configured for a database that contains FILESTREAM filegroups.
• Database mirroring is not supported with either cross-database transactions or distributed transactions. For more information.