Migrate on-premises virtual machines

8 minutes

Migrating your on-premises workloads to Azure involves various phases. You’ve completed the planning and assessment, and prepared the environment and VMs for migration.

The next phase is to track and monitor the replication process, before running a full migration to Azure. You’ll run a test migration in a non-production environment to ensure that your VMs can successfully migrate to Azure before finally cutting over to a full migration.

In this unit, you'll review the replication process and components involved. You’ll also learn how to track and monitor each phase of the migration process.

Replication process

The replication process consists of several steps, beginning with a Start Replication job.

On successful completion of the Start Replication job, the VMs start their initial replication to Azure.
During initial replication, a Hyper-V VM snapshot it taken. The Azure Site Recovery provider and Azure Recovery Service agent work together to replicate data from Hyper-V VMs to Azure. The replicated data is uploaded to a storage account in the Azure subscription.
Disk data from the snapshot is replicated to Hyper-V Replica managed disks in Azure. The replica disks are used to create the Azure VMs when you migrate.
Hyper-V Replica tracks disk changes during initial replication, and changes are stored in log files.
On completion of initial replication, the VM snapshot is deleted, and delta replication starts.
The Recovery Services agent periodically uploads replication logs to a log storage account.

Diagram of the Replication workflow. Numbered steps (1-6) show the process from the Start Replication job, to the initial replication and delta replication phases. Components that are part of the replication workflow are shown and the text in the content has an equivalent numbered list that explains each step in the process.

Required components for replication

The first time you replicate any VMs, Azure Migrate Server Migration sets up additional resources in the Azure Migrate project’s resource group. These resources are used to manage and orchestrate the replication process, and store replication information.

The resources used by Azure Migrate Server Migration are

Service bus: Sends replication orchestration information to the Azure Migrate appliance
Gateway storage account: Stores VM state information
Log storage account: stores replication logs
Key vault: Manages connection strings for the service bus, and access keys for the storage accounts used in replication

Track replication job status

During the replication process, you can track when initial replication changes to delta replication. You can also monitor the status of the replicating machines by clicking on Replicating servers in Azure Migrate: Server Migration.

Screenshot of the Azure Migrate: Server Migration panel. Overview button and Replicating servers are highlighted with a red border.

Azure Migrate Server Migration indicates the status of the replicating machines. Each Replication job has successfully completed, and three machines are now replicating. Each machine shows a status of healthy with no issues needing attention.

Screenshot that displays the overview page with the status of the replication jobs in Azure Migrate: Server Migration. The screenshot shows the following: Step 1: Replicate is highlighted with a red border to show the status of the currently replicating machines. 3 machines are shown with a status of healthy. There are panels for Step 2: Test Migration and Step 3: Migrate.

Complete initial replication

The length of time to complete replication depends on factors that include VM size, available space on the host for log file storage, network bandwidth and target storage in Azure. You have already accounted for this in the planning phase.

Initial replication completes when the status of each machine changes from In progress to Protected.

Click Replicating machines.
Refresh occasionally until all machines show status of Protected.

Screenshot of the Replicating machines blade. Under overview, Replicating machines is highlighted with a red border and numbered 1. On the right side, 3 VMs are listed showing Status of Protected, and a Health status of Healthy. Test Migration status show a status of Never performed.

Run a test migration

Before completing a full migration, you’ll run a test migration for each VM. This lets you see if the migration works as you expected. As part of the preparation to migrate, you’ve already set up a non-production Azure virtual network for testing. A test migration creates a set of Azure VMs from the replicated data and migrates them to the non-production VNet.

You can run the test migration when delta replication begins, allowing replication of the on-premises machines to continue without impact. You use the replicated test Azure VMs to confirm the migration works correctly, and address any issues before full migration.

In Migration goals > Servers > Azure Migrate: Server Migration, click Test migrated servers.
Right-click the VM to test, and click Test migrate.

Screenshot of the Replicating machines blade. Under Manage, Replicating machines shows one VM in Delta sync with a Health status of Healthy and showing the Migration Phase as Test migration pending.

Newly-created Azure VMs are migrated to your non-production Azure VNet. You can monitor the test migration job in the portal notifications. After the test migration completes, view the migrated VMs in the Azure portal. You’ll notice that new VMs with a -Text suffix have been created.

After verifying the test migration results, perform a test migration cleanup. Under Migration Phase, status changes to Test clean up pending.

Migrate the VMs

Having verified that your migration works as expected, you’re ready to complete the migration of your on-premises servers. The final migration is very similar to the test migration process.

You can choose to have Azure Migrate shut down the on-premises VMs and run an on-demand replication to synchronize any VM changes that occurred since the last replication occurred. As you’re running a small pilot migration to learn more about using Azure Migrate, there’s no requirement to keep your on-premises VMs running. This prevents any data loss.

Like the previous phases, a migration job starts for each VM. You can track and monitor progress as before. Wait till all Planned failover jobs show a status of Successful.

Screenshot of the Jobs blade. Under Manage, Jobs is highlighted with a red border and numbered 1. On the right side Job status information is shown for 3 VMs. The 3 VMs are highlighted with a red border and numbered 2. The screenshot shows the VMs as going through a Planned failover that is currently in progress.

Navigate to the resource group associated with the Azure Migrate project and verify that the VM, network interface, and disk resources have been created for each of the virtual machines being created.

Complete post migration tasks

When complete, you’ll stop the migration. Azure Migrate stops replication and cleans up replication state information for the VMs.

After migrating your VMs, you want to be able to perform common tasks, like installing and configuring software. This requires enabling and running Azure virtual machine extensions. To do this, you’ll need to install an Azure Virtual Machine agent on the migrated machines. The Azure documentation provides information about the Azure VM agents for Windows and Linux.

You didn’t migrate any databases for the pilot, but had you done so, this is the time to update any database connection strings, or web server configurations.

After your stakeholders perform final application and migration acceptance testing, cut over traffic to the migrated Azure VM instances. Finally, remove on-premises VMs from your local VM inventory and local backups.

In the next unit, you’ll look at some best practices you can do to increase the security of your VMs that are now running in Azure.

Check your knowledge

During replication, what does a status of Protected indicate for a virtual machine?

Critical issues have been encountered for the VM during replication.

The VM state is healthy and is ready for migration.

Initial replication is complete and delta replication can begin.

What happens to a Hyper-V VM during delta replication?

VHDs on the VM are replicated one-by-one until they are all copied to Azure.

Incremental changes to on-premises disks are periodically replicated to Azure.

A Hyper-V VM snapshot is created, and disk changes are tracked using Hyper-V Replica.

You must answer all questions before checking your work.

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