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Create a managed disk from a snapshot with CLI (Linux)

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This article contains two scripts for creating a managed disk from a snapshot. The first script is for a managed disk with platform-managed keys and the second script is for a managed disk with customer-managed keys. Use these scripts to restore a virtual machine from snapshots of OS and data disks. Create OS and data managed disks from respective snapshots and then create a new virtual machine by attaching managed disks. You can also restore data disks of an existing VM by attaching data disks created from snapshots.

If you don't have an Azure subscription, create an Azure free account before you begin.

Prerequisites

Sample script

Launch Azure Cloud Shell

The Azure Cloud Shell is a free interactive shell that you can use to run the steps in this article. It has common Azure tools preinstalled and configured to use with your account.

To open the Cloud Shell, just select Try it from the upper right corner of a code block. You can also launch Cloud Shell in a separate browser tab by going to https://shell.azure.com.

When Cloud Shell opens, verify that Bash is selected for your environment. Subsequent sessions will use Azure CLI in a Bash environment, Select Copy to copy the blocks of code, paste it into the Cloud Shell, and press Enter to run it.

Sign in to Azure

Cloud Shell is automatically authenticated under the initial account signed-in with. Use the following script to sign in using a different subscription, replacing <Subscription ID> with your Azure Subscription ID. If you don't have an Azure subscription, create an Azure free account before you begin.

subscription="<subscriptionId>" # add subscription here

az account set -s $subscription # ...or use 'az login'

For more information, see set active subscription or log in interactively

Disks with platform-managed keys

#Provide the subscription Id of the subscription where you want to create Managed Disks
subscriptionId="<subscriptionId>"

#Provide the name of your resource group
resourceGroupName=myResourceGroupName

#Provide the name of the snapshot that will be used to create Managed Disks
snapshotName=mySnapshotName

#Provide the name of the new Managed Disks that will be create
diskName=myDiskName

#Provide the size of the disks in GB. It should be greater than the VHD file size.
diskSize=128

#Provide the storage type for Managed Disk. Acceptable values are Standard_LRS, Premium_LRS, PremiumV2_LRS, StandardSSD_LRS, UltraSSD_LRS, Premium_ZRS, and StandardSSD_ZRS.
storageType=Premium_LRS

#Required for Premium SSD v2 and Ultra Disks
#Provide the Availability Zone you'd like the disk to be created in, default is 1
zone=1

#Set the context to the subscription Id where Managed Disk will be created
az account set --subscription $subscriptionId

#Get the snapshot Id 
snapshotId=$(az snapshot show --name $snapshotName --resource-group $resourceGroupName --query [id] -o tsv)

#Create a new Managed Disks using the snapshot Id
#Note that managed disk will be created in the same location as the snapshot
#If you're creating a Premium SSD v2 or an Ultra Disk, add "--zone $zone" to the end of the command
az disk create --resource-group $resourceGroupName --name $diskName --sku $storageType --size-gb $diskSize --source $snapshotId

Disks with customer-managed keys

#Provide the subscription Id of the subscription where you want to create Managed Disks
subscriptionId="<subscriptionId>"

#Provide the name of your resource group
resourceGroupName=myResourceGroupName

#Provide the name of the snapshot that will be used to create Managed Disks
snapshotName=mySnapshotName

#Provide the name of the new Managed Disks that will be create
diskName=myDiskName

#Provide the size of the disks in GB. It should be greater than the VHD file size.
diskSize=128

#Provide the storage type for Managed Disk. Premium_LRS or Standard_LRS.
storageType=Premium_LRS

#Provide the name of the target disk encryption set
diskEncryptionSetName=myName

#Provide the target disk encryption set resource group
diskEncryptionResourceGroup=myGroup

#Required for Premium SSD v2 and Ultra Disks
#Provide the Availability Zone you'd like the disk to be created in, default is 1
zone=1

#Set the context to the subscription Id where Managed Disk will be created
az account set --subscription $subscriptionId

#Get the snapshot Id 
snapshotId=$(az snapshot show --name $snapshotName --resource-group $resourceGroupName --query [id] -o tsv)

#Get the disk encryption set ID
diskEncryptionSetId=$(az disk-encryption-set show --name $diskEncryptionSetName --resource-group $diskEncryptionResourceGroup)

#Create a new Managed Disks using the snapshot Id
#Note that managed disk will be created in the same location as the snapshot
#To change the location, add the --location parameter
#If you're creating a Premium SSD v2 or an Ultra Disk, add "--zone $zone" to the end of the command
az disk create -g $resourceGroupName -n $diskName --source $snapshotId --disk-encryption-set $diskEncryptionSetID --location eastus2euap

Performance impact - background copy process

When you create a managed disk from a snapshot, it starts a background copy process. You can attach a disk to a VM while this process is running but you'll experience performance impact (4k disks experience read impact, 512e experience both read and write impact) with higher latency, lower IOPS and throughput until background copy completes. For Ultra Disks and Premium SSD v2, you can check the status of the background copy process with the following commands:

Important

You can't use the following sections to get the status of the background copy process for disk types other than Ultra Disk or Premium SSD v2. Other disk types will always report 100%.

subscriptionId=yourSubscriptionID
resourceGroupName=yourResourceGroupName
diskName=yourDiskName
az account set --subscription $subscriptionId
az disk show -n $diskName -g $resourceGroupName --query [completionPercent] -o tsv

Clean up resources

Run the following command to remove the resource group, VM, and all related resources.

az group delete --name myResourceGroupName

Sample reference

This script uses following commands to create a managed disk from a snapshot. Each command in the table links to command specific documentation.

Command Notes
az snapshot show Gets all the properties of a snapshot using the name and resource group properties of the snapshot. ID property is used to create managed disk.
az disk create Creates a managed disk using snapshot ID of a managed snapshot

Next steps

Create a virtual machine by attaching a managed disk as OS disk

For more information on the Azure CLI, see Azure CLI documentation.

More virtual machine and managed disks CLI script samples can be found in the Azure Linux VM documentation.