Migrate a Linux virtual machine from unmanaged disks to managed disks

Article
03/08/2023

Applies to: ✔️ Linux VMs

If you have existing Linux virtual machines (VMs) that use unmanaged disks, you can migrate the VMs to use Azure Managed Disks. This process converts both the OS disk and any attached data disks.

This article shows you how to migrate VMs by using the Azure CLI. If you need to install or upgrade it, see Install Azure CLI.

Before you begin

Review the FAQ about migration to Managed Disks.

The migration will restart the VM, so schedule the migration of your VMs during a pre-existing maintenance window.
The migration isn't reversible.
Any users with the Virtual Machine Contributor role won't be able to change the VM size (as they could pre-migration). This is because VMs with managed disks require the user to have the Microsoft.Compute/disks/write permission on the OS disks.
Be sure to test the migration. Migrate a test virtual machine before you perform the migration in production.
During the migration, you deallocate the VM. The VM receives a new IP address when it's started after the migration. If needed, you can assign a static IP address to the VM.
Review the minimum version of the Azure VM agent required to support the migration process. For information on how to check and update your agent version, see Minimum version support for VM agents in Azure

The original VHDs and the storage account used by the VM before migration are not deleted. They continue to incur charges. To avoid being billed for these artifacts, delete the original VHD blobs after you verify that the migration is complete. If you need to find these unattached disks in order to delete them, see our article Find and delete unattached Azure managed and unmanaged disks.

Migrate single-instance VMs

This section covers how to migrate single-instance Azure VMs from unmanaged disks to managed disks. (If your VMs are in an availability set, see the next section.) You can use this process to migrate the VMs from premium (SSD) unmanaged disks to premium managed disks, or from standard (HDD) unmanaged disks to standard managed disks.

Deallocate the VM by using az vm deallocate. The following example deallocates the VM named myVM in the resource group named myResourceGroup:
```
az vm deallocate --resource-group myResourceGroup --name myVM
```
Migrate the VM to managed disks by using az vm convert. The following process converts the VM named myVM, including the OS disk and any data disks:
```
az vm convert --resource-group myResourceGroup --name myVM
```
Start the VM after the migration to managed disks by using az vm start. The following example starts the VM named myVM in the resource group named myResourceGroup.
```
az vm start --resource-group myResourceGroup --name myVM
```

Migrate VMs in an availability set

If the VMs that you want to migrate to managed disks are in an availability set, you first need to migrate the availability set to a managed availability set.

All VMs in the availability set must be deallocated before you migrate the availability set. Plan to migrate all VMs to managed disks after the availability set itself has been converted to a managed availability set. Then, start all the VMs and continue operating as normal.

List all VMs in an availability set by using az vm availability-set list. The following example lists all VMs in the availability set named myAvailabilitySet in the resource group named myResourceGroup:
```
az vm availability-set show \
    --resource-group myResourceGroup \
    --name myAvailabilitySet \
    --query [virtualMachines[*].id] \
    --output table
```
Deallocate all the VMs by using az vm deallocate. The following example deallocates the VM named myVM in the resource group named myResourceGroup:
```
az vm deallocate --resource-group myResourceGroup --name myVM
```
Migrate the availability set by using az vm availability-set convert. The following example converts the availability set named myAvailabilitySet in the resource group named myResourceGroup:
```
az vm availability-set convert \
    --resource-group myResourceGroup \
    --name myAvailabilitySet
```
Migrate all the VMs to managed disks by using az vm convert. The following process converts the VM named myVM, including the OS disk and any data disks:
```
az vm convert --resource-group myResourceGroup --name myVM
```
Start all the VMs after the migration to managed disks by using az vm start. The following example starts the VM named myVM in the resource group named myResourceGroup:
```
az vm start --resource-group myResourceGroup --name myVM
```

Migrate using the Azure portal

You can also migrate unmanaged disks to managed disks using the Azure portal.

Sign in to the Azure portal.
Select the VM from the list of VMs in the portal.
In the blade for the VM, select Disks from the menu.
At the top of the Disks blade, select Migrate to managed disks.
If your VM is in an availability set, there will be a warning on the Migrate to managed disks blade that you need to migrate the availability set first. The warning should have a link you can click to migrate the availability set. Once the availability set is converted or if your VM is not in an availability set, click Migrate to start the process of migrating your disks to managed disks.

The VM will be stopped and restarted after migration is complete.

Next steps

For more information about storage options, see Azure Managed Disks overview.