One of the most tricky subject for any SQL Server DBA or SQL server consultant How to build HA ( High Availability ) it is not something Complex, but it need to be list down all of the points and the requirements before going for this project and when we talk about High Availability We should consider two technology FCI (SQL Server Failover Cluster) and AOAG (Always on High Availability Group) both technologies will give you the same feature ( High Availability ) to save your DB from any disaster can be happened in your DB center , As you know AOAG is new technology released with SQL Server 2012 and Microsoft added more features on it in SQL Server 2016, 2017 and 2019 as well . So really I recommend it for HA solution. Also, it will give you the availability to split your transaction between multiple instance one as RW (Read-write) it is called Primary, and the other instance will work as R (Read only), and it is called secondary server.
Now I leave you with the training video to know How you can build SQL Server HA and DR using FCI and AOAG
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