Common questions - VMware to Azure replication

This article provides answers to common questions when you're deploying disaster recovery of on-premises VMware VMs to Azure.


What do I need for VMware VM disaster recovery?

Learn about the components involved in disaster recovery of VMware VMs.

Can I use Site Recovery to migrate VMware VMs to Azure?

Yes, in addition to using Site Recovery to set up full disaster recovery for VMware VMs, you can also use Site Recovery to migrate on-premises VMware VMs to Azure. In this scenario you replicate on-premises VMware VMs to Azure storage. Then, you fail over from on-premises to Azure. After failover, your apps and workloads are available and running on Azure VMs. The process is similar to setting up full disaster recovery, except that in a migration you can't fail back from Azure.

Does my Azure account need permissions to create VMs?

If you're a subscription administrator, you have the replication permissions you need. If you're not, you need permissions to create an Azure VM in the resource group and virtual network you specify when you configure Site Recovery, and permissions to write to the selected storage account or managed disk based on your configuration. Learn more.

What applications can I replicate?

You can replicate any app or workload running on a VMware VM that complies with replication requirements.

  • Site Recovery provides support for application-aware replication, so that apps can be failed over and failed back to an intelligent state.
  • Site Recovery integrates with Microsoft applications such as SharePoint, Exchange, Dynamics, SQL Server and Active Directory, and works closely with leading vendors, including Oracle, SAP, IBM and Red Hat.
  • Learn more about workload protection.

Can I use a guest OS server license on Azure?

Yes, Microsoft Software Assurance customers can use Azure Hybrid Benefit to save on licensing costs for Windows Server machines that are migrated to Azure, or to use Azure for disaster recovery.


What access does Site Recovery need to VMware servers?

Site Recovery needs access to VMware servers to:

  • Set up a VMware VM running the Site Recovery configuration server,
  • Automatically discover VMs for replication.

What access does Site Recovery need to VMware VMs?

  • In order to replicate, an VMware VM must have the Site Recovery Mobility service installed and running. You can deploy the tool manually, or specify that Site Recovery should do a push installation of the service when you enable replication for a VM.
  • During replication, VMs communicate with Site Recovery as follows:
    • VMs communicate with the configuration server on port HTTPS 443 for replication management.
    • VMs send replication data to the process server on port HTTPS 9443 (can be modified).
    • If you enable multi-VM consistency, VMs communicate with each other over port 20004.

Is replication data sent to Site Recovery?

No, Site Recovery doesn't intercept replicated data, and doesn't have any information about what's running on your VMs. Replication data is exchanged between VMware hypervisors and Azure storage. Site Recovery has no ability to intercept that data. Only the metadata needed to orchestrate replication and failover is sent to the Site Recovery service.

Site Recovery is ISO 27001:2013, 27018, HIPAA, DPA certified, and is in the process of SOC2 and FedRAMP JAB assessments.


How can I calculate approximate charges for VMware disaster recovery?

You can use the pricing calculator to estimate costs while using Site Recovery.

For detailed estimate on costs, run the deployment planner tool for VMware, and use the cost estimation report.

Is there any difference in cost between replicating to storage or directly to managed disks?

Managed disks are charged slightly different than storage accounts. Learn more about managed disk pricing.

Mobility service

Where can I find the Mobility service installers?

The installers are in the %ProgramData%\ASR\home\svsystems\pushinstallsvc\repository folder on the configuration server.

How do I install the Mobility service?

You install on each VM you want to replicate, using a number of methods:

Managed disks

Where does Site Recovery replicate data to?

Site Recovery replicates on-premises VMware VMs and physical servers to managed disks in Azure.

  • The Site Recovery process server writes replication logs to a cache storage account in the target region.
  • These logs are used to create recovery points on the managed disks.
  • When failover occurs, the recovery point you select is used to create the target managed disk.
  • VMs that were previously replicated to a storage account (prior to March 2019) aren't affected.

Can I replicate new machines to storage accounts?

No, beginning March 2019, in the portal, you can replicate only to Azure managed disks.

Replication of new VMs to a storage account is only available using PowerShell or the REST API (version 2018-01-10 or 2016-08-10).

What are the benefits in replicating to managed disks?

Learn how Site Recovery simplifies disaster recovery with managed disks.

Can I change the managed disk type after machine is protected?

Yes, you can easily change the type of managed disk. Before changing the type, ensure that you revoke the SAS URL for the disk by going to the Managed Disk resource on the Azure portal. From the overview blade, cancel any ongoing export. Once the SAS URL is revoked, change the type of the disk within the next few minutes. However, if you change the managed disk type, wait for fresh recovery points to be generated by Azure Site Recovery. Use the new recovery points for any test failover or failover going forward.

Can I switch replication from managed disks to unmanaged disks?

No, switching from managed to unmanaged isn't supported.


What are the replicated VM requirements?

Learn more about VMware VM/physical server requirements and support.

How often can I replicate to Azure?

Replication is continuous when replicating VMware VMs to Azure.

Can I extend replication?

Extended or chained replication isn't supported. Request this feature in feedback forum.

Can I do an offline initial replication?

This isn't supported. Request this feature in the feedback forum.

Can I exclude disks from replication?

Yes, you can exclude disks.

Can I replicate VMs with dynamic disks?

Dynamic disks can be replicated. The operating system disk must be a basic disk.

If I use replication groups for multi-VM consistency, can I add a new VM to an existing replication group?

Yes, you can add new VMs to an existing replication group when you enable replication for them.

  • You can't add a VM to an existing replication group after replication is initiated.
  • You can't create a replication group for existing VMs.

Can I modify VMs that are replicating by adding or resizing disks?

For VMware replication to Azure you can modify disk size. If you want to add new disks you need to add the disk and reenable protection for the VM.

Can I migrate on-premises machines to a new vCenter Server without impacting ongoing replication?

No, change of Vcenter or migration will impact ongoing replication. You need to set up Site Recovery with the new vCenter Server, and enable replication for machines again.

Can I replicate to a cache/target storage account which has a VNet (with Azure storage firewalls) configured on it?

No, Site Recovery doesn't support replication to Storage on Vnet.

Component upgrade

My version of the Mobility services agent or configuration server is old and my upgrade failed. What do I do?

Site Recovery follows the N-4 support model. Learn more about how to upgrade from very old versions.

Where can I find the release notes/update rollups of Azure Site Recovery?

Learn about new updates, and get rollup information.

Where can I find upgrade information for disaster recovery to Azure?

Learn about upgrading.

Do I need to reboot source machines for each upgrade?

Though recommended, it is not mandatory for each upgrade. Learn more.

Configuration server

What does the configuration server do?

The configuration server runs the on-premises Site Recovery components, including:

  • The configuration server itself that coordinates communications between on-premises and Azure and manages data replication.
  • The process server that acts as a replication gateway. It receives replication data; optimizes it with caching, compression, and encryption; and sends it to Azure storage. The process server also does a push install of the Mobility Service on VMs, and performs automatic discovery of on-premises VMware VMs.
  • The master target server that handles replication data during failback from Azure.

Learn more about the configuration server components and processes.

Where do I set up the configuration server?

You need a single highly available on-premises VMware VM for the configuration server. For physical server disaster recovery, you can install the configuration server on a physical machine.

What do I need for the configuration server?

Review the prerequisites.

Can I manually set up the configuration server instead of using a template?

We recommend that you create the configuration server VM with the latest version of the OVF template. If for some reason you can't, for example you don't have access to the VMware server, you can download the setup file from the portal and set up the configuration server.

Can a configuration server replicate to more than one region?

No. To do this, you need a configuration server in each region.

Can I host a configuration server in Azure?

While possible, the Azure VM running the configuration server would need to communicate with your on-premises VMware infrastructure and VMs. This adds latency and impacts ongoing replication.

How do I update the configuration server?

Learn how to update configuration server.

  • You can find the latest update information on the Azure updates page.
  • You can download the latest version from the portal. Alternatively, you can directly download the latest version of the configuration server from the Microsoft Download Center.
  • If your version is more than four versions older than the current version, refer to our support statement for upgrade guidance.

Should I back up the configuration server?

We recommend taking regular scheduled backups of the configuration server.

  • For successful failback, the VM being failed back must exist in the configuration server database.
  • The configuration server must be running and in a connected state.
  • Learn more about common configuration server management tasks.

When I'm setting up the configuration server, can I download and install MySQL manually?

Yes. Download MySQL and place it in the C:\Temp\ASRSetup folder. Then install it manually. When you set up the configuration server VM and accept the terms, MySQL will be listed as Already installed in Download and install.

Can I avoid downloading MySQL but let Site Recovery install it?

Yes. Download the MySQL installer and place it in the C:\Temp\ASRSetup folder. When you set up the configuration server VM, accept the terms, and click on Download and install. The portal will use the installer you added to install MySQL.

Can I use the configuration server VM for anything else?

No, you should only use the VM for the configuration server.

Can I clone a configuration server and use it for orchestration?

No, you should set up a fresh configuration server to avoid registration issues.

Can I change the vault in which the configuration server is registered?

No. After a vault is associated with the configuration server, it can't be changed. Review this article to learn about re-registering.

Can I use the same configuration server for disaster recovery of both VMware VMs and physical servers

Yes, but note that physical machine can only be failed back to a VMware VM.

Where can I download the passphrase for the configuration server?

Learn how to download the passphrase.

Where can I download vault registration keys?

In the Recovery Services vault, click Configuration Servers in Site Recovery Infrastructure > Manage. Then in Servers, select Download registration key to download the vault credentials file.

Failover and failback

Can I use the process server at on-premises for failback?

We strongly recommended creating a process server in Azure for failback purposes, to avoid data transfer latencies. Additionally, in case you separated the source VMs network with the Azure facing network in the configuration server, it's essential to use the process server created in Azure for failback.

Can I retain the IP address on failover?

Yes, you can retain the IP address on failover. Ensure that you specify target IP address in 'Compute and Network' settings for the VM before failover. Also, shut down machines at the time of failover to avoid IP address conflicts during failback.

Can I change the target VM size or VM type before failover?

Yes, you can change the type or size of the VM anytime before failover on the Compute and Network settings of the replicated Vm, in the portal.

How far back can I recover?

For VMware to Azure the oldest recovery point you can use is 72 hours.

How do I access Azure VMs after failover?

After failover, you can access Azure VMs over a secure Internet connection, over a site-to-site VPN, or over Azure ExpressRoute. You'll need to prepare a number of things in order to connect. Learn more

Is failed over data resilient?

Azure is designed for resilience. Site Recovery is engineered for failover to a secondary Azure datacenter, in accordance with the Azure SLA. When failover occurs, we make sure your metadata and vaults remain within the same geographic region that you chose for your vault.

Is failover automatic?

Failover isn't automatic. You initiate failovers with single click in the portal, or you can use PowerShell to trigger a failover.

Can I fail back to a different location?

Yes, if you failed over to Azure, you can fail back to a different location if the original one isn't available. Learn more.

Why do I need a VPN or ExpressRoute to fail back?

When you fail back from Azure, data from Azure is copied back to your on-premises VM and private access is required.

Can I resize the Azure VM after failover?

No, you cannot change the size or type of the target VM after the failover.

Automation and scripting

Can I set up replication with scripting?

Yes. You can automate Site Recovery workflows using the Rest API, PowerShell, or the Azure SDK.Learn more.

Performance and capacity

Can I throttle replication bandwidth?

Yes. Learn more.

Next steps

  • Review support requirements.
  • Set up VMware to Azure replication.