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Appendix: AlwaysOn Availability support for
SQL Server

The AlwaysOn Availability Groups feature is a high-availability and disaster-recovery solution that provide an enterprise-level alternative to database mirroring. Introduced in
SQL Server
2012, AlwaysOn Availability Groups maximize the availability of a set of user databases for an enterprise that is running SQL Server 2012, 2014, 2016, or 2017. An availability group supports a failover environment for a discrete set of user databases, known as availability databases, that fail over together. A read-scale availability group is a group of databases that perform read-only work and are copied from other
SQL Server
An availability group supports a set of read-write primary databases and one to eight sets of corresponding secondary databases. Optionally, secondary databases can be made available for read-only access and some backup operations.
For more information about AlwaysOn availability, visit to read Overview of Always On Availabilty Groups.