Using Microsoft Azure Virtual Machines as replicas

One of the new features of 2014 is the ability to combine your on-premise AlwaysOn Availability Group instances and also maintain a replica on Microsoft Azure Virtual Machine. This feature allows you to combine the flexibility and control of managing your own infrastructure along with maintaining a secondary stored site in the Microsoft Azure data centers.

The commit mode

Earlier in this chapter, we described AlwaysOn Availability Groups as database mirroring on steroids. Like database mirroring, AlwaysOn Availability Groups have two modes that you can choose from when configuring each replica:

The asynchronous commit mode: We can choose this commit mode when performance is more important than protecting against data loss. If every replica is running in the asynchronous commit mode, then the primary replica will not wait for any acknowledgement from the secondary replica that implies the transaction has been written to the log of secondary...