Understand database mirroring requirements for disaster recovery purposes

SharePoint 2010 is mirroring aware and utilizes the FailoverPartner keyword in its database connection strings to identify a SQL Server instance that is used for mirroring purposes. Upon learning this, it might be tempting to jump right in and start mirroring SharePoint databases for redundancy. Before doing so, though, you should be aware that the following requirements apply:

• Less than 1ms latency between principal and mirror SQL Server instances
• 1GB/s bandwidth or greater between principal and mirror SQL Server instances
• Principal and mirror instances must be running the same version and edition of SQL Server
• Mirrored databases must use the Full recovery model
• High safety with automatic failover (that is, synchronous mirroring with witness server) is recommended

Mirroring is certainly useful, but as the aforementioned list demonstrates: it shouldn’t be implemented without careful planning and infrastructure design.