One-click replication for Azure Virtual Machines with Azure Site Recovery

Problem Statement

A typical enterprise application comprises of multiple virtual machines spanning different application tiers. A single tier will likely have two or more virtual machines for redundancy and load balancing. To recover your applications in the event of a disaster, you need a solution that facilitates the recovery of the application as a whole.

Using traditional backup solutions to achieve application disaster recovery is extremely cumbersome, error prone and not scalable. Even many replication based software only recover individual virtual machines and cannot handle the complexity of bringing up a functioning enterprise application. Also, there is no guarantee that the application running in the virtual machines will work because a crash-consistent recovery point does not ensure correctness of application data.

Solution

Azure Site Recovery (ASR) combines a unique cloud-first design with a simple user experience to offer a powerful solution that lets you recover entire applications in the event of a disaster. Azure Site Recovery not only supports application consistency for a single virtual machine, it also supports application consistency across multiple virtual machines that compose the application.

ASR is now built into the virtual machine experience so that you can setup replication in one click for your Azure virtual machines. Combined with ASR’s one-click failover capabilities, its simpler than ever before to setup replication and test a disaster recovery scenario. This new service allows you to take your existing Azure production workloads and configure them for replication and recovery into a separate Azure Region. Once configured, ASR will continuously replicate your virtual machines and allow you to orchestrate the recovery of these VMs into another region in the event of a disaster.

Why use Site Recovery?

A common myth around protecting your applications is the fact that many applications come with in-built replication technologies - hence the question, why do you need Azure Site Recovery?

The simple answer:

Replication != Disaster Recovery

Site Recovery provides a simple way to replicate Azure VMs between regions:

·         Automatic deployment. Unlike an active-active replication model, there's no need for an expensive and complex infrastructure in the secondary region. When you enable replication, Site Recovery automatically creates the required resources in the target region, based on source region settings.

·         Control regions. With Site Recovery, you can replicate from any region to any region within a continent. Compare this with read-access geo-redundant storage, which replicates asynchronously between standard paired regions only. Read-access geo-redundant storage provides read-only access to the data in the target region.

·         Automated replication. Site Recovery provides automated continuous replication. Failover and failback can be triggered with a single click.

·         Testing. You can run disaster-recovery drills with on-demand test failovers, as and when needed, without affecting your production workloads or ongoing replication.

·         Recovery plans. You can use recovery plans to orchestrate failover and failback of the entire application running on multiple VMs. The recovery plan feature has rich first-class integration with Azure automation runbooks.

·         Cost savings. If your DR VMs aren’t active, then you are only paying the ASR fee plus storage and network egress. You are not paying for any running VMs, which is the bulk of the cost in any DR environment.

How to set up Site Recovery?

Here's a summary of what you need to do to set up replication of VMs between Azure regions:

1. Create a Recovery Services vault. The vault contains configuration settings and orchestrates replication.
2. Enable replication for the Azure VMs.
3. Run a test failover to make sure that everything's working as expected.

View the detailed steps to set up Site Recovery here.

Limitations:

·         No support for VMs with managed disks yet.

·         Windows Server 2016 Nano Server is not supported.

·         Linux support limited to certain distributions.

·         Management is currently only through the Azure Portal — no support for command line, PowerShell, or REST yet.

·         Virtual Machine Scale sets not supported.

·         Azure Disk Encryption is not supported.

·         Replication groups (the ability to group VMs so they can be replicated and recover to the same recovery point) is not yet available.

References:

• https://azure.microsoft.com/en-us/blog/simplified-disaster-recovery-for-azure-iaas-vms/
• https://docs.microsoft.com/en-us/azure/site-recovery/site-recovery-support-matrix-azure-to-azure
• https://azure.microsoft.com/en-us/blog/simplified-disaster-recovery-for-azure-iaas-vms/