How can businesses protect on-premises workloads by utilizing hybrid environments using the Azure public cloud? Let's look at two Microsoft products, Azure Backup and Azure Site Recovery, and see how they compare and contrast to protect data at both the VM level and the site level.

Today, many businesses leverage public clouds in a major way as part of their BCDR strategy.  Utilizing cloud storage for offsite backup storage as well as VM replication are two very popular use cases for protecting on-premises resources.

Microsoft Azure is a predominant public cloud environment in use by businesses today and is a great place to store backups and replicate virtual machines.  For seamless replication and integration with Azure for on-premises VMs, Microsoft has two different tools that you can make use of to perform replication and backups from on-premises to your Microsoft Azure IaaS environment.

Let's take a look at Azure Backup vs. Azure Site Recovery and see how these two tools are used, how they are different, and what use case each allows businesses to solve.

What is Azure Backup?

In the simplest of explanations, Azure Backup is a service that allows you to back up your data to the Microsoft Azure Cloud.  This includes both on-premises VMs and Azure VMs.  Azure Backup is a service that can supplement existing backup solutions or replace existing solutions altogether.  Organizations who may look at Azure Backup can decide if Azure Backup can potentially replace existing solutions, as this could certainly lead to cost savings.

Many businesses today are evolving in the way that they store and archive their data.  Traditionally, tape backups have served as the medium for retaining data long term, which is often necessary due to regulatory requirements.  Services like Azure Backup can potentially eliminate the need to store backups offsite on tape backups, as data is essentially stored "offsite" in secure data storage in Microsoft Azure.

What are the benefits of Azure Backup?

There are several benefits to utilizing the Azure Backup service.  These include:

  • Simplifying your on-premises backup architecture – Azure Backup allows you to easily create the architecture and environment you need to back up your on-premises resources to the Microsoft Azure cloud.
  • Consolidating Backup solutions between Azure and on-premises – If you are running in a hybrid environment, Azure Backup allows for the simplification of the means to back up resources in both locations. This includes the ability to back up on-premises and Azure IaaS VMs.
  • Scaling with Azure – Scaling storage, compute, network, and other resources can become difficult with on-premises infrastructure constraints. When you use the Azure Backup service, you have the scalability of Azure working for you.
  • No charge for data transfer – With Azure Backup, you are not charged for the amount of inbound or outbound data that is transferred. Generally, with cloud environments, you are charged when you get your data out of the environment.  However, with Azure Backup, there is no charge for the inbound or outbound data.  The only caveat is large amounts of data imported using the Azure Import/Export service.
  • Data encryption – Azure Backup data is encrypted both in flight and at rest.
  • Take application-consistent backups – This is key when backing up consistency sensitive database-driven applications like SQL Server, Exchange Server, and SharePoint.
  • You can also protect file servers and Windows clients, allowing you to protect and restore client files and folders granularly.
  • Protection is not cloud-specific – Azure Backup can protect workloads running in any cloud, including hosted, public, or private clouds.
  • Virtually unlimited restore points – You can decide how many restore points you want to keep. Azure allows keeping a limit of 9999 recovery points per protected instance, so virtually unlimited.
  • Pay-as-you-use storage model – You only pay for the amount of storage you use, and you are not charged for your own on-premises storage.
  • Azure Backup utilizes Azure redundancy and high-availability options – You can choose to keep your storage highly available using Azure locally redundant storage (LRS), which keeps three copies of your data in a storage scale unit in a datacenter. Alternatively, you can use geo-redundant storage (GRS), which replicates data to a secondary region that is hundreds of miles away. GRS is the recommended option.

Azure Backup architecture

The Azure Backup architecture performs backups of VMs and data using a number of approaches.  These can be broken down by their architecture based on two different types of backup scenarios:

  • On-premises Windows machines
  • Azure IaaS VMs

Azure Backup on-premises Windows machines

There are two means to back up on-premises Windows machines using Azure backup.  These are:

  • Backing up directly to Azure by means of the Microsoft Azure Recovery Services (MARS) agent
  • Backing up in a two-step approach using an on-premises backup server, including either DPM or Microsoft Azure Backup Server (MABS). The backup server then can replicate the backups to a Recovery Services vault in Azure.

Azure Backup Azure IaaS VMs to Recovery Services vault

As you would imagine, the Azure Backup service can back up Azure resources running in the Azure IaaS offering.  This includes Azure VMs.  There are basically three ways you can back up Azure VMs using Azure Backup.  These are:

  • By using a specialized backup agent extension, Azure Backup can back up Azure IaaS VMs. This enables an entire VM backup
  • You can install the MARS agent and back up specific files and folders of Azure VMs
  • You can run the Azure Backup Server as a VM in Azure IaaS as you would configure it on-premises and have it back up to the Azure Recovery services vault.

Below is an example of how to begin the process of configuring backups in Azure using Azure Backup.

Beginning the process of Enabling Azure Backup on an Azure IaaS VM

Beginning the process of Enabling Azure Backup on an Azure IaaS VM

What is Azure Site Recovery?

A key aspect of BCDR is site-level data protection.  What happens if you lose an entire production site?  This moves past the need to simply restore a backup.  Site recovery involves orchestrating failovers and failbackups from one site to another in an automated fashion.  Azure Site Recovery is a tool that allows you to perform this orchestration and automate the replication of Azure VMs between regions, on-premises virtual machines, and physical servers to Azure.

Azure Site Recovery includes the ability to replicate your data from one datacenter to another.  The other datacenter in this solution would be the Azure IaaS environment in the cloud.

Azure Site Recovery can perform replications for Azure VMs between Azure regions and on-premises VMs, Azure Stack VMs, and physical servers.

While Azure Backup focuses on backups, Azure Site Recovery is more a replication mechanism.

What are the benefits of Azure Site Recovery?

Azure Site Recovery has many capabilities and benefits.  These include:

  • Simplified site recovery, allowing replication, failover, and failback within the Azure console
  • Replication between Azure regions
  • Replication from on-premises to Azure or to a secondary on-premises datacenter
  • Multiple platform support – This includes Azure VMs, Hyper-V, VMware, and physical workloads
  • Extremely aggressive replication – With ASR, you can replicate as frequently as every 30 seconds for Hyper-V and continuously for Azure and VMware VMs
  • Application consistent replication
  • Test your failovers and failbacks in a simulated way
  • Planned failovers, customized recovery plans, and network integration with Azure makes the recoverability offered by ASR extremely seamless and flexible.

Azure Site Recovery architecture

As an example, let's take a look at the architectural components for VMware vSphere VM replication via Azure Site Recovery.

VMware to Azure Architecture via Azure Site Recovery

VMware to Azure Architecture via Azure Site Recovery

Azure Site Recovery is configured as an on-premises appliance via a VMware vSphere OVA appliance.  This "combined" process and config server is the mediator between the on-premises vSphere environment and Azure.  The ASR config server makes the connection to both VMware vSphere and Azure.

Deploying the Azure Site Recovery appliance

Deploying Azure Site Recovery is accomplished by deploying the Azure Site Recovery configuration server.  The configuration server is the appliance that manages the replication of VMs between datacenters.  In the case of on-premises VMware environments, Microsoft has an OVA appliance that is available for download for easy deployment in your VMware vSphere environment.

Ready to complete the deployment process of the Azure Site Recovery OVA in VMware

Ready to complete the deployment process of the Azure Site Recovery OVA in VMware

Once the appliance is downloaded and deployed, you go through a configuration wizard that configures the appliance network connection, the connection to Azure, and the connection to your on-premises VMware vSphere environment, among other things.

Add vCenter Server and vSphere ESXi host dialog box

Add vCenter Server and vSphere ESXi host dialog box

Once the on-premises appliance is up and running the required on-premises infrastructure, the rest of the configuration takes place in Microsoft Azure.

Configuring the Azure Site Recovery configuration in Azure

Configuring the Azure Site Recovery configuration in Azure

The Azure configuration is completed by assigning the replication settings in the Azure portal and the source and target environments, as well as selecting the objects to replicate.

Azure Backup vs. Azure Site Recovery

With an overview of both services in mind, which do you choose?  Azure Backup and Azure Site Recovery realistically should not be thought of as competing products.  Rather, they are complimentary.  Azure Backup allows for granular backups and restores specific data.  Azure Site Recovery allows for the protection of an entire production site with automation and orchestration to make the failover and failback processes seamless.

A few points to consider:

Subscribe to 4sysops newsletter!

  • When thinking about data backup and retention, Azure Backup allows many more granular backup and retention policies compared to Azure Site Recovery.
  • For very specific data restores, Azure Backup is the solution that would allow the data to be restored and recovered in specific data loss events.
  • When using Azure Site Recovery, RPOs can drastically be reduced since Site Recovery provides continuous or extremely low replication intervals between the source and replica copies in Azure. Azure Backup RPOs will be higher.
  • RTOs are lower with Azure Site Recovery as with Azure Backup; a large amount of data may need to be recovered to restore data.

Wrapping up

Azure Backup and Azure Site Recovery are both powerful tools for backing up and replicating data between on-premises and Azure environments.  It comes down to choosing the right tool for the job and use case. Both products provide needed functionality in protecting individual workloads as well as protecting workloads at a site level.  They are complementary data protection products intended to cover the full gamut of data protection needs in the enterprise.  Both simplify the infrastructure and architecture needed to utilize hybrid environments for satisfying 3-2-1 backup objectives and storing data offsite using the Azure public cloud.

  1. Rory Schmitz 3 years ago


    Good write-up and thank you for the comparison.  In regards to Azure Backup/ASR and VMware-based VMs, where in the process does the VMDK-based VM turn into a usable/bootable Azure VHD?  I've always struggled to understand this.  How frequently can ASR replicate to meet existing RPO/RTO's?

  2. Gillian 7 months ago

    Great article! Thanks 🙂

Leave a reply

Please enclose code in pre tags

Your email address will not be published.


© 4sysops 2006 - 2023


Please ask IT administration questions in the forums. Any other messages are welcome.


Log in with your credentials


Forgot your details?

Create Account