Availability Zones in Azure provide enhanced resiliency by protecting applications and data from datacenter-level failures. Each Availability Zone consists of one or more datacenters with independent power, cooling, and networking. Azure ensures high availability by offering a minimum of three physically separate zones in every zone‑enabled region. This physical isolation within a region helps safeguard workloads against localized outages. Using Availability Zones, Azure provides a 99.99% virtual machine (VM) uptime SLA. Support for Availability Zones is available only in select Azure regions, as listed in Regions with Availability Zones.
This scenario describes using Azure Site Recovery–based migration to move VMs from a non‑zonal deployment to zonal deployments, improving availability by placing them in Availability Zones in a (usually different) target region. Azure separates this into two main cases: single‑instance VMs and VMs currently in availability sets.
Single-instance VMs → Zones in target region
When you have standalone VMs (not in availability sets) in a source region:
- You enable Azure Site Recovery replication from the source region to a target region that supports Availability Zones and supports the required VM sizes.
- During failover planning, you map each replicated VM to a specific zone (for example, Zone 1, Zone 2, or Zone 3) in the target region and choose a compatible zonal VM SKU and networking.
VMs in availability sets → Zones in target region
When your VMs are in availability sets in the source region and you want zonal resiliency:
- You configure Site Recovery for each VM in the availability set, targeting the same region but different zones or a new region with zones.
- In the target region, you map each VM into an appropriate Availability Zone (often distributing them across zones) instead of recreating the availability set structure, thereby achieving fault‑domain isolation at the zone level.
Step-by-Step Guide: Enable Replication and Move Azure VMs into Availability Zones Using Azure Site Recovery
Enable Replication
The following steps guide you through enabling data replication to the target region using Azure Site Recovery (ASR), prior to moving your virtual machines into Availability Zones.
Note
These steps demonstrate the process for a single virtual machine, but you can apply the same steps to multiple VMs. In the Recovery Services vault, select + Replicate, then select and enable replication for multiple VMs together.
1. Select the VM to Replicate
- In the Azure portal, go to Virtual machines.
- Select the VM you want to move into Availability Zones.
- Under Backup + disaster recovery, choose Disaster recovery.
2. Configure the Target Region
- Under Configure disaster recovery > Target region, select the target region for replication.
Ensure the region supports Availability Zones. - Select Next: Advanced settings.
- Specify:
- Target subscription
- Target VM resource group
- Target virtual network
- In the Availability section, choose the Availability Zone you want the VM to be moved into.
Note
If the options for availability set or Availability Zone do not appear, verify that all prerequisites and source VM preparation steps have been completed.
- Select Enable Replication to start the replication job.
Check Settings
After the replication job completes, you can verify replication status and adjust replication settings.
- In the VM menu, select Disaster recovery.
- Review:
- Replication health
- Created recovery points
- Source and target region mapping
Test the Configuration
- In the VM menu, select Disaster recovery.
- Choose Test Failover.
Choose a recovery point:
- Latest processed
Uses the latest processed recovery point—fastest RTO. - Latest app-consistent
Uses the most recent application-consistent point. - Custom
Select any available recovery point.
Select the test target network
Choose the Azure virtual network to use for the test failover.
Important
Use a separate test network, not the production network in the target region.
- Select OK to begin the test.
Track progress by:- Opening the VM’s properties, or
- Viewing Site Recovery jobs under
Vault name > Settings > Jobs > Site Recovery jobs
- After the test failover completes, the replica VM appears under Virtual machines.
Validate:- VM boots correctly
- VM size is correct
- Networking is configured properly
- To delete the test VM, select Cleanup test failover on the replicated item and add any notes as needed.
Move to the Target Region and Confirm
- In the VM menu, select Disaster recovery.
- Choose Failover.
- In Failover, select Latest.
- Enable Shut down machine before beginning failover.
ASR will attempt to shut down the source VM, but failover continues even if shutdown fails.
You can monitor progress on the Jobs page.
After Failover Completes
- Confirm the VM appears in the target region’s Availability Zone.
- During the finalization stage:
- In Replicated items, right-click the VM and select Commit.
- Wait for the commit job to finish.
This completes the move to the target region and Availability Zone.
Step-by-Step Guide: Enable Replication and Move Azure VMs into Availability Zones Using Azure Site Recovery
Enable Replication
The following steps guide you through enabling data replication to the target region using Azure Site Recovery (ASR), prior to moving your virtual machines into Availability Zones.
Note
These steps demonstrate the process for a single virtual machine, but you can apply the same steps to multiple VMs. In the Recovery Services vault, select + Replicate, then select and enable replication for multiple VMs together.
1. Select the VM to Replicate
- In the Azure portal, go to Virtual machines.
- Select the VM you want to move into Availability Zones.
- Under Backup + disaster recovery, choose Disaster recovery.
2. Configure the Target Region
- Under Configure disaster recovery > Target region, select the target region for replication.
Ensure the region supports Availability Zones. - Select Next: Advanced settings.
- Specify:
- Target subscription
- Target VM resource group
- Target virtual network
- In the Availability section, choose the Availability Zone you want the VM to be moved into.
Note
If the options for availability set or Availability Zone do not appear, verify that all prerequisites and source VM preparation steps have been completed.
- Select Enable Replication to start the replication job.
Check Settings
After the replication job completes, you can verify replication status and adjust replication settings.
- In the VM menu, select Disaster recovery.
- Review:
- Replication health
- Created recovery points
- Source and target region mapping
Test the Configuration
- In the VM menu, select Disaster recovery.
- Choose Test Failover.
Choose a recovery point:
- Latest processed
Uses the latest processed recovery point—fastest RTO. - Latest app-consistent
Uses the most recent application-consistent point. - Custom
Select any available recovery point.
Select the test target network
Choose the Azure virtual network to use for the test failover.
Important
Use a separate test network, not the production network in the target region.
- Select OK to begin the test.
Track progress by:- Opening the VM’s properties, or
- Viewing Site Recovery jobs under
Vault name > Settings > Jobs > Site Recovery jobs
- After the test failover completes, the replica VM appears under Virtual machines.
Validate:- VM boots correctly
- VM size is correct
- Networking is configured properly
- To delete the test VM, select Cleanup test failover on the replicated item and add any notes as needed.
Move to the Target Region and Confirm
- In the VM menu, select Disaster recovery.
- Choose Failover.
- In Failover, select Latest.
- Enable Shut down machine before beginning failover.
ASR will attempt to shut down the source VM, but failover continues even if shutdown fails.
You can monitor progress on the Jobs page.
After Failover Completes
- Confirm the VM appears in the target region’s Availability Zone.
- During the finalization stage:
- In Replicated items, right-click the VM and select Commit.
- Wait for the commit job to finish.
This completes the move to the target region and Availability Zone.
Reference: Move Azure virtual machines into Availability Zones
