In many of the screencast in this series I have moved a VM around my demo setup, however there has only been the one copy of it whether it was on a scale-out file server, in a cluster or both. In any production environment you would want to augment this with additional disaster recovery techniques including have a backup of the key virtual machines somewhere.
Replica in Windows Server 2012 is a partial answer to this. You setup a process to make an offline copy of a given virtual machine (VM) on another server and continually keep it updated. This replica VM can be updated over “UK speed” (don’t get me started!) broadband and you can also maintain up to 4 roiling snapshots enabling you to go back past a data error you may want to correct. This screencast shows you how to set it up ..
The replica is always off and it’s up to you under what conditions you invoke failover and of course you can script this in PowerShell with Start-VMFailover as well as all of the configuration for Replica I did in the screencast.
The principal and replica can either be a cluster or an individual server.
In my demo all the servers belong to the same domain but if that’s not the case then you can use CredSSP to set this up. One use of this is that hosters are planning to offer replica as a service so you’ll be able to set your critical VMs to be replicated (is that English?) over the internet into their data centres as a service.
As I briefly mention in the screencast you can also set your replicated VM to preserve it’s network settings when you fail over to it in its new location,