High-availability feature of SQL Server that keeps synchronous or asynchronous replicas on different servers or VMs without shared storage. As every replica is a live SQL Server, it is an expensive way to provide DR.
Also called AG, AG.
Read more: Microsoft Learn
In the Ultra Transcenders books
Each book explains Always On availability group in context, with comparison tables and the common traps.
Terms in this definition
- Microsoft SQL Server
Microsoft's database engine. It can hold Veeam's configuration database in place of PostgreSQL, and is protected with a dedicated plug-in, Veeam Explorer, and application-aware processing plus log backup.
- Virtual machines
Infrastructure-as-a-service compute giving complete control of the operating system, making it a fit for lift-and-shift moves and for software relying on OS-level pieces like COM.
- General-purpose v1
The older storage account kind (
Storage), which lacks access tiers, Archive and premium file shares and retires on 13 October 2026. Converting to ZRS requires first upgrading to GPv2, a one-way change. - Azure AI Search replica
Additional copy of a search service's engine and indexes. Replicas spread queries for load balancing and improve availability, so adding them is the fix when queries are throttled with HTTP 503.