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--- title: Create an incremental snapshot description: Learn about incremental snapshots for managed disks, including how to create them and the performance impact when restoring snapshots. author: roygara ms.service: azure-disk-storage ms.topic: how-to ms.date: 08/19/2026 ms.author: rogarana ms.custom: devx-track-azurepowershell, devx-track-azurecli, references_regions ms.devlang: azurecli # Customer intent: As a cloud administrator, I want to create incremental snapshots for managed disks, so that I can efficiently back up and restore disk data while minimizing storage costs and improving performance. --- # Create an incremental snapshot for managed disks **Applies to:** :heavy_check_mark: Linux VMs :heavy_check_mark: Windows VMs :heavy_check_mark: Flexible scale sets :heavy_check_mark: Uniform scale sets Incremental snapshots are point-in-time backups for managed disks that, when taken, consist only of the changes since the last snapshot. The first incremental snapshot is a full copy of the disk. The subsequent incremental snapshots occupy only delta changes to disks since the last snapshot. When you restore a disk from an incremental snapshot, the system reconstructs the full disk that represents the point in time backup of the disk when the incremental snapshot was taken. This capability for managed disk snapshots potentially allows them to be more cost-effective, since, unless you choose to, you don't have to store the entire disk with each individual snapshot. Just like full snapshots, incremental snapshots can be used to either create a full managed disk or a full snapshot. Snapshots of Premium SSD, Standard SSD, and Standard HDD disks can be used immediately after they're created. Incremental snapshots of Ultra Disk and Premium SSD v2 disks can't be used until the background data copy finishes unless you [enable instant access](disks-instant-access-snapshots.md#create-an-instant-access-snapshot) when you create the snapshot. There are a few differences between an incremental snapshot and a full snapshot. Incremental snapshots use Standard HDD storage, regardless of the source disk's storage type, whereas full snapshots can use Premium SSD storage. If you're using full snapshots on Premium SSD storage to scale up VM deployments, use custom images on Standard HDD storage in the [Azure Compute Gallery](/azure/virtual-machines/shared-image-galleries). It helps you achieve a more massive scale with lower cost. Additionally, incremental snapshots potentially offer better reliability with [zone-redundant storage](/azure/storage/common/storage-redundancy) (ZRS). If ZRS is available in the selected region, an incremental snapshot uses ZRS automatically. If ZRS isn't available in the region, then the snapshot defaults to [locally redundant storage](/azure/storage/common/storage-redundancy) (LRS). You can override this behavior and select one manually but, we don't recommend that. Incremental snapshots are billed for the used size only. You can find the used size of your snapshots by looking at the [Azure usage report](/azure/cost-management-billing/understand/review-individual-bill). For example, if the used data size of a snapshot is 10 GiB, the **daily** usage report shows 10 GiB/(31 days) = 0.3226 as the consumed quantity. ## Restrictions [!INCLUDE [virtual-machines-disks-incremental-snapshots-restrictions](./includes/virtual-machines-disks-incremental-snapshots-restrictions.md)] ## Create incremental snapshots # [Azure CLI](#tab/azure-cli) You can use the Azure CLI to create an incremental snapshot. You need the latest version of the Azure CLI. See the following articles to learn how to either [install](/cli/azure/install-azure-cli) or [update](/cli/azure/update-azure-cli) the Azure CLI. The following script creates an incremental snapshot of a particular disk: ```azurecli # Declare variables diskName="yourDiskNameHere" resourceGroupName="yourResourceGroupNameHere" snapshotName="desiredSnapshotNameHere" # Get the disk you need to backup yourDiskID=$(az disk show -n $diskName -g $resourceGroupName --query "id" --output tsv) # Create the snapshot az snapshot create -g $resourceGroupName -n $snapshotName --source $yourDiskID --incremental true ``` You can identify incremental snapshots from the same disk with the `SourceResourceId` property. This property contains the Azure Resource Manager resource ID of the source disk. Use `SourceResourceId` to [list all incremental snapshots associated with a particular disk](#cli---list-incremental-snapshots). # [Azure PowerShell](#tab/azure-powershell) You can use the Azure PowerShell module to create an incremental snapshot. You need the latest version of the Azure PowerShell module. The following command will either install it or update your existing installation to latest: ```PowerShell Install-Module -Name Az -AllowClobber -Scope CurrentUser ``` Once that is installed, sign in to your PowerShell session with `Connect-AzAccount`. To create an incremental snapshot with Azure PowerShell, set the configuration with [New-AzSnapShotConfig](/powershell/module/az.compute/new-azsnapshotconfig) with the `-Incremental` parameter and then pass that as a variable to [New-AzSnapshot](/powershell/module/az.compute/new-azsnapshot) through the `-Snapshot` parameter. ```PowerShell $diskName = "yourDiskNameHere" $resourceGroupName = "yourResourceGroupNameHere" $snapshotName = "yourDesiredSnapshotNameHere" # Get the disk that you need to backup by creating an incremental snapshot $yourDisk = Get-AzDisk -DiskName $diskName -ResourceGroupName $resourceGroupName # Create an incremental snapshot by setting the SourceUri property with the value of the Id property of the disk $snapshotConfig=New-AzSnapshotConfig -SourceUri $yourDisk.Id -Location $yourDisk.Location -CreateOption Copy -Incremental New-AzSnapshot -ResourceGroupName $resourceGroupName -SnapshotName $snapshotName -Snapshot $snapshotConfig ``` You can identify incremental snapshots from the same disk by using the `SourceResourceId` and `SourceUniqueId` properties. `SourceResourceId` contains the Azure Resource Manager resource ID of the source disk. `SourceUniqueId` contains the value inherited from the disk's `UniqueId` property. If you delete a disk and then create a new disk with the same name, the disk's `UniqueId` value changes. You can use `SourceResourceId` and `SourceUniqueId` to create a list of all snapshots associated with a particular disk. Replace `yourResourceGroupNameHere` with your value and then you can use the following example to list your existing incremental snapshots: ```PowerShell $resourceGroupName = "yourResourceGroupNameHere" $snapshots = Get-AzSnapshot -ResourceGroupName $resourceGroupName $incrementalSnapshots = New-Object System.Collections.ArrayList foreach ($snapshot in $snapshots) { if($snapshot.Incremental -and $snapshot.CreationData.SourceResourceId -eq $yourDisk.Id -and $snapshot.CreationData.SourceUniqueId -eq $yourDisk.UniqueId){ $incrementalSnapshots.Add($snapshot) } } $incrementalSnapshots ``` # [Portal](#tab/azure-portal) [!INCLUDE [virtual-machines-disks-incremental-snapshots-portal](./includes/virtual-machines-disks-incremental-snapshots-portal.md)] # [Resource Manager Template](#tab/azure-resource-manager) You can also use Azure Resource Manager templates to create an incremental snapshot. You'll need to make sure the apiVersion is set to **2022-03-22** and that the incremental property is also set to true. The following snippet is an example of how to create an incremental snapshot with Resource Manager templates: ```json { "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#", "contentVersion": "1.0.0.0", "parameters": { "diskName": { "type": "string", "defaultValue": "contosodisk1" }, "diskResourceId": { "defaultValue": "<your_managed_disk_resource_ID>", "type": "String" } }, "resources": [ { "type": "Microsoft.Compute/snapshots", "name": "[concat( parameters('diskName'),'_snapshot1')]", "location": "[resourceGroup().location]", "apiVersion": "2022-03-22", "properties": { "creationData": { "createOption": "Copy", "sourceResourceId": "[parameters('diskResourceId')]" }, "incremental": true } } ] } ``` --- ## Check snapshot status Incremental snapshots of Premium SSD v2 or Ultra Disks can't be used to create new disks until the background process copying the data into the snapshot has completed. You can use either the [CLI](#cli) or [PowerShell](#powershell) sections to check the status of the background copy from a disk to a snapshot. > [!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. Snapshots of other disk types always report 100%. ### CLI You have two options for getting the status of snapshots. You can either get a [list of all incremental snapshots associated with a specific disk](#cli---list-incremental-snapshots), and their respective status, or you can get the [status of an individual snapshot](#cli---individual-snapshot). #### CLI - List incremental snapshots The following script returns a list of all snapshots associated with a particular disk. The value of the `CompletionPercent` property of any snapshot must be 100 before it can be used. Replace `yourResourceGroupNameHere`, `yourSubscriptionId`, and `yourDiskNameHere` with your values then run the script: ```azurecli # Declare variables and create snapshot list subscriptionId="yourSubscriptionId" resourceGroupName="yourResourceGroupNameHere" diskName="yourDiskNameHere" az account set --subscription $subscriptionId diskId=$(az disk show -n $diskName -g $resourceGroupName --query [id] -o tsv) az snapshot list --query "[?creationData.sourceResourceId=='$diskId' && incremental]" -g $resourceGroupName --output table ``` #### CLI - Individual snapshot You can also check the status of an individual snapshot by checking the `CompletionPercent` property. Replace `$sourceSnapshotName` with the name of your snapshot then run the following command. The value of the property must be 100 before you can use the snapshot for restoring disk or generate a SAS URI for downloading the underlying data. ```azurecli az snapshot show -n $sourceSnapshotName -g $resourceGroupName --query [completionPercent] -o tsv ``` ### PowerShell You have two options for getting the status of snapshots. You can either get a [list of all incremental snapshots associated with a particular disk](#powershell---list-incremental-snapshots) and their respective status, or you can get the [status of an individual snapshot](#powershell---individual-snapshots). #### PowerShell - List incremental snapshots The following script returns a list of all incremental snapshots associated with a particular disk that haven't completed their background copy. Replace `yourResourceGroupNameHere` and `yourDiskNameHere`, then run the script. ```azurepowershell $resourceGroupName = "yourResourceGroupNameHere" $snapshots = Get-AzSnapshot -ResourceGroupName $resourceGroupName $diskName = "yourDiskNameHere" $yourDisk = Get-AzDisk -DiskName $diskName -ResourceGroupName $resourceGroupName $incrementalSnapshots = New-Object System.Collections.ArrayList foreach ($snapshot in $snapshots) { if($snapshot.Incremental -and $snapshot.CreationData.SourceResourceId -eq $yourDisk.Id -and $snapshot.CreationData.SourceUniqueId -eq $yourDisk.UniqueId) { $targetSnapshot=Get-AzSnapshot -ResourceGroupName $resourceGroupName -SnapshotName $snapshotName { if($targetSnapshot.CompletionPercent -lt 100) { $incrementalSnapshots.Add($targetSnapshot) } } } } $incrementalSnapshots ``` #### PowerShell - individual snapshots You can check the `CompletionPercent` property of an individual snapshot to get its status. Replace `yourResourceGroupNameHere` and `yourSnapshotName` then run the script. The value of the property must be 100 before you can use the snapshot for restoring disk or generate a SAS URI for downloading the underlying data. ```azurepowershell $resourceGroupName = "yourResourceGroupNameHere" $snapshotName = "yourSnapshotName" $targetSnapshot=Get-AzSnapshot -ResourceGroupName $resourceGroupName -SnapshotName $snapshotName $targetSnapshot.CompletionPercent ``` ## Check sector size Snapshots with a 4096 logical sector size can only be used to create Premium SSD v2 or Ultra Disks. They can't be used to create other disk types. Snapshots of disks with 4096 logical sector size are stored as VHDX, whereas snapshots of disks with 512 logical sector size are stored as VHD. Snapshots inherit the logical sector size from the parent disk. To determine whether your Premium SSD v2 or Ultra Disk snapshot is a VHDX or a VHD, get the `LogicalSectorSize` property of the snapshot. The following command displays the logical sector size of a snapshot: ```azurecli az snapshot show -g resourcegroupname -n snapshotname --query [creationData.logicalSectorSize] -o tsv ``` ## Next steps See the following articles to create disks from your snapshots using the [Azure CLI](scripts/create-managed-disk-from-snapshot.md) or [Azure PowerShell module](scripts/virtual-machines-powershell-sample-create-managed-disk-from-snapshot.md). See [Copy an incremental snapshot to a new region](disks-copy-incremental-snapshot-across-regions.md) to learn how to copy an incremental snapshot across regions. If you have more questions, see the [snapshots](/azure/virtual-machines/faq-for-disks#snapshots) section of the FAQ. If you'd like to see sample code demonstrating the differential capability of incremental snapshots, using .NET, see [Copy Azure managed disks backups to another region with differential capability of incremental snapshots](https://github.com/Azure-Samples/managed-disks-dotnet-backup-with-incremental-snapshots).