Mirroring, clustering and availability groups

Take a seat, put down any hot drinks and prepare to be shocked: mirroring has been deprecated. This may come as quite a jolt to anyone who reads it, as it did to us, the authors. To use a more accurate SQL Profiler term, mirroring has been marked for deprecation. This means it will almost certainly still be available for the next two editions of SQL Server. In practice, it is probably going to be close to 2020 by the time we have to worry about it. By this time, availability groups should be as good, if not better than mirroring, in every sense.

There is a perception that availability groups replace clustering, but this is not the case. Clustering allows failover at the SQL Server instance level, whereas availability groups fail over at the database level. However, availability groups do employ the services of Windows Server Failover Clustering (WSFC), quite simply because it made more sense to use a technology that was tried and tested, rather...