Creating an AlwaysOn Availability Group
In this recipe, we will create an Availability Group in the primary instance.
Getting ready
It is worth having a refresher on some of the AlwaysOn terminology:
- A primary is the active instance and is the source of all the updates. This was referred to as the principal in database mirroring.
- A secondary is the instance that receives all the updates from the primary. In database mirroring, this was referred to as the mirror and was unreadable because it was left in the restoring state. In AlwaysOn, there can be up to four secondary replicas with different synchronization modes. Secondary replicas can also be readable.
- An Availability Group defines the unit of a failover. This includes defining the group of user databases called availability databases, which will failover together. According to MSDN, an availability group supports a set of primary databases and one to eight sets of corresponding secondary databases. An availability group also identifies the...
