acknowledged as part of a runbook execution. The final step is to enable virtual
machines for protection using ASR via SCVMM, which behind the scenes configures
the virtual machine to use Hyper-V Replica and makes the replication known to ASR.
The option to use ASR can also be made part of a virtual machine template in
SCVMM. This makes it easy to let the user deploy virtual machines that will be
protected with Hyper-V Replica.
In the event a failover is required, one of the defined recovery plans can be initiated
that triggers workflows on the SCVMM servers to perform the orchestrator Hyper-V
Replica failovers and reverse replication as required.
As this high-level overview shows, no virtual machine or data ever goes to Microsoft
Azure. All replication is directly between Hyper-V hosts in the organization’s
datacenters. The ASR service in Windows Azure is simply communicating with the
SCVMM instances at each location to help orchestrate the initial configuration of
Hyper-V Replica between the hosts, enabling replication for virtual machines and then
triggering workflows to perform failovers, all from a separate cloud-based location.
Maintaining an entire second datacenter just for the purposes of disaster recovery is
an expensive proposition for any organization, and ASR offers an alternate option for
Hyper-V virtual machines—which is replicating to Azure, as shown in Figure 8.12. In
this deployment mode, which can work through SCVMM or direct from Hyper-V hosts
without SCVMM management, the Hyper-V Replica replication is to Azure, where the
virtual hard disks are stored in an Azure Storage account. A mapping is still created
between the on-premises network; however, its target is now a virtual subnet in an
Azure virtual network. In the figure, I show a virtual machine. This does not exist,
however, during normal replication. The virtual machine is only created in the event
of a failover, and at that time it is connected to the replicated VHD file, and any
pending HRL files are merged into the VHD in the Azure storage account. This
approach of creating the VM only when needed optimizes Azure spend, since compute
charges will be more than storage. If you view the storage account, a VM is replicated
into in Azure. You will see both a VHD container (the Azure storage equivalent of a
folder) and an HRL container, which contains the Hyper-V Replica log files that have
not yet been merged into the target VHD.