Azure Site Recovery: disaster recovery of Virtual Machines in Azure

In azure, there is the possibility of using Azure Site Recovery (ASR) to implement easily an efficient disaster recovery strategy by enabling replication of virtual machines among different regions of Azure. Although in Azure are present integrated mechanisms to deal with localized hardware failures, it may be appropriate to implement a solution that can ensure applications compliance , performed on virtual machines in Azure, against both catastrophic events, such as earthquakes or hurricanes, that software issues that may impact on the functioning of an entire region of Azure. This article will show you how to configure a virtual machine replication and how to enable a disaster recovery scenario.

This feature has been defined one-click replication because of its simplicity, it is currently in public preview and it is usable in all the Azure regions where ASR is available.

Before you enable this functionality is essential to ensure that the necessary requirements are met and to do that you can see the compatibility matrix for the replication scenario of virtual machines among different regions.

By accessing the Azure Portal it is possible to select the virtual machine that you intend to replicate and perform the configuration in the section Disaster recovery:

Figure 1 – Disaster Recovery Section of the VM

Selecting Disaster Recovery shows the following configuration panel:

Figure 2 – VM replication configuration panel

The first required parameter is the target region where you want to replicate the virtual machine. The replication activation process also create the necessary Azure artifacts (Resource Group, Availability Set if used by the selected VM, Virtual Network and Storage accounts) or you can select them at will if they were created earlier.

Figure 3 – The resources needed in the region target

The replication process also requires the presence of a Cache Storage Accounts in the source region that is used as a temporary repository to store changes before they are reported in the storage account defined in the target region. This is done to minimize the impact on production applications that reside on the replicated VM.

Figure 4 - Cache Storage Account in the replication process

Always in the configuration panel is required which is proposed Vault Recovery Services use creating a replication policy that defines the recovery point retention and the rate at which consistent snapshots are made at the application level.

By selecting Enable Replication will begin the creation process of Azure resources required, the VM is registered in the selected Recovery Services Vault and replication process is activated.

The Disaster Recovery section lists details about the replication and it is possible to perform a failover or a test failover:

Figure 5 - Details relating to the replication process of the VM and activation of the failover process

The procedure Test Failover Specifies which recovery point using between: latest, latest processed, latest app-consistent or custom. In addition it is possible to select in which virtual network attest the virtual machine during the test failover in order to perform the test without generating any impact on the production systems.

Figure 6 – Test Failover of a VM

Similar the Failover panel that allows you to specify only which recovery point to use as the network on which attest the machine has already been defined in the configuration phase.

Figure 7 – Failover of a VM

Only when you start the Failover process affected virtual machines are created on the target resource group, attested to the target vNet and configured in the availability set appropriate when used.

Figure 8 – Failover process

Conclusions

Thanks to this new feature introduced in Azure Site Recovery it is possible to activate with ease replication of virtual machines in different Azure regions, without the necessity of having expensive secondary infrastructure to activate a disaster recovery plan.