Azure Site Recovery

Azure Site Recovery (ASR) enables the recovery management capabilities for OMS. ASR is a service in Microsoft Azure that facilitates your disaster recovery and business continuity strategy by enabling you to replicate, failover, and recover your workloads in the event of a failure. With ASR, you can replicate on-premises VMWare, Hyper-V VMs and Windows and Linux physical servers to either Azure storage or to a secondary datacenter. You can also use ASR to replicate Azure VMs to another Azure region.

ASR supports the replication of VMs in the following scenarios:

• Replication and recovery to and from Azure of on-premises Hyper-V VMs on Hyper-V standalone hosts and clusters that are managed with or without System Center Virtual Machine Manager (VMM)
• Replication and recovery to and from Azure of on-premises VMWare VMs
• Replication and recovery to and from Azure of on-premises physical servers
• Replication and recovery to and from secondary datacenters of on-premises Hyper-V VMs on Hyper-V standalone hosts and clusters that are managed in VMM clouds
• Replication and recovery to and from secondary datacenters of on-premises VMWare VMs
• Replication and recovery to and from secondary datacenters of on-premises Windows and Linux physical servers
• Replication and recovery of Azure VMs from one Azure region to another

The ASR replication process varies according to the scenario you implement, and will be explored in greater detail in Chapter 4, Protecting and Recovering Data with OMS, of this book. In general, if replicating workloads to Azure from an on premises location, you will need to set up requirements for the Azure components, including an Azure account, a storage account, and an Azure network.

For VMWare VMs and Physical server replication to Azure, you will also need ASR component servers (configuration and process servers) and a master target server for failback. You will need to set up a Recovery Services vault in Azure, which is the storage entity that houses the data in Azure. In the vault, you can specify the replication target and source, set up the configuration server, add sources, define your replication policy, and perform other recovery tasks, such as test failovers and failbacks.

Similarly, for replicating Hyper-V VMs to Azure, if the hosts are configured in VMM clouds, you can register the VMM server(s) in the Recovery Services vault and install the Site Recovery Provider to orchestrate replication with Azure. If hosts are not located in VMM clouds, then you will install the Site Recovery Provider directly on the hosts.

Once the infrastructure is set up and the replication configured, protected on-premises machines will replicate an initial copy of the data, after which delta changes will be replicated. Traffic is then replicated over the secure internet connection or Azure ExpressRoute to Azure storage endpoints. For Azure VMWare VMs and Windows/Linux physical servers, this traffic can also be replicated over a site-to-site VPN connection.

For Azure VM replication, you will need to enable Azure VM replication in the Azure portal, after which resources are created automatically in the target region that you designate. Once replication is enabled, the Site Recovery Extension Mobility Service will be installed automatically on the Azure VM and will then be registered with Site Recovery, and then the VM will be configured for continuous replication. At this point, any data written to the Azure VM disks will continuously get transferred to the cache storage account in the source environment. Site Recovery will then process the data and send it to the target storage account in the target environment.

ASR also provides you with failover testing and the failover of protected resources to a target protection environment (Azure or a secondary site), as well as the ability to fail back to the source site. The following figure depicts the ASR data flow for the replicated data of protected resources from the source location to the target location in Azure or a secondary site: