FAQ for remote NVMe disks

The DiskControllerTypes is defined during VM configuration and is determined by the selected VM size as either NVMe or Small Computer System Interface (SCSI). If you don't specify a DiskControllerTypes value, the platform automatically chooses the default controller based on the VM size configuration.

To enable the remote NVMe interface on your VM, you must meet the following prerequisites:

• Most modern Azure VM sizes support the NVMe disk controller type for remote storage. Support begins with Ebsv5 VM sizes and later generations (v6, v7).

• Select the operating system image that's tagged with NVMe support. For VM sizes that support the NVMe interface, Azure automatically configures the NVMe disk controller type during VM creation. The NVMe setting in the Advanced tab is selected by default and cannot be changed.

  

• Opt in to NVMe by selecting the NVMe disk controller type in the Azure portal or in the Azure Resource Manager, Azure CLI, or Azure PowerShell template. For step-by-step instructions, refer to the general NVMe FAQ.

You can use the following process to either:

• Resize a SCSI-based VM created using an untagged image to an NVMe-enabled VM of a different size without re-creating the VM configurations and without tagging the image.
• Resize a SCSI-based VM to an NVMe-enabled VM of a different size without re-creating the VM configurations.

The source VM can be either:

• An untagged OS image that supports remote NVMe.
• An NVMe-tagged OS image.

To resize the VM, use the following command to run an Azure PowerShell script that sets the destination discontrollertype value of the VM as NVMe:

azure-nvme-VM-update.ps1 [-subscription_id] <String> [-resource_group_name] <String> [-vm_name] <String> [[-disk_controller_change_to] <String>] [-vm_size_change_to] <String> [[-start_vm_after_update] <Boolean>] [[-write_logfile] <Boolean>]

For more details, refer to SCSI to NVMe for Linux VMs

To check if an image is tagged as NVMe, use the following command:

az vm image show --urn URN_OF_IMAGE

To create an image definition that supports NVMe for remote disks, complete the following steps:

1. Upload an NVMe-supported virtual hard disk (VHD) to your storage account. AzCopy is a fast way, but you can also use the portal to upload.

   azcopy copy <local path to your VHD> <container in your storage account>
   

2. Create an image gallery by using Azure PowerShell, the portal, or the Azure CLI.

3. Create an image definition. Be sure to include --feature DiskControllerTypes=SCSI,NVMe.

   Here's an Azure CLI example:

   az sig image-definition create --resource-group <resourceGroupName> --gallery-name <galleryName> --gallery-image-definition <imageName> --publisher <publisher> --offer <offerName> --sku <skuName> --os-type <osType> --os-state <osState> --feature DiskControllerTypes=SCSI,NVMe
   

4. Create the image version with the NVMe-supported VHD.

   Here's an Azure CLI example:

   az sig image-version create --resource-group <resourceGroupName> --gallery-name <galleryName> --gallery-image-definition <imageName> --gallery-image-version <version> --target-regions <region1> <region2> --replica-count <replicaCount> --os-vhd-uri <NVMe-supported vhd uri> --os-vhd-storage-account <storageAccount>
   

NVMe sizes can be combined with Azure Standard HDD, Standard SSD, Premium SSD v1, Premium SSD v2, and Ultra Disk Storage. For more information on Azure disk offerings, see Azure managed disk types.

Live resizing of NVMe is supported on Azure Premium SSD v1 disks, Premium SSD v2 disks, Standard SSD disks, and Standard HDD disks. You can also add remote NVMe disks without restarting the VM.

1. Get the nvme-cli package:

   sudo apt install nvme-cli
   

2. Run the NVMe list command to fetch NVMe disk details:

   sudo nvme list
   

   

   

   Here's how the data appears in response to Azure PowerShell commands:

   

Open Azure PowerShell and use the following command:

wmic diskdrive get model,scsilogicalunit

The ASAP attached disks are presented in the guest with the model string Virtual_Disk NVMe Premium. The SCSI logical unit has the value for the portal-visible LUN ID incremented by 1.

Here's a snapshot of how NVMe disks appear in an NVMe-enabled Windows VM:

The following snapshot shows guest output for data disks attached at LUN 0 and LUN 4 (CRP). The LUN ID is equivalent to the namespace ID.

The shared disk feature is supported for Premium SSD, Premium SSD v2, and Ultra Disk Storage disks. Shared Disks using NVMe isn't supported with the OS Windows Server 2019.

Yes. A data disk can be detached from a SCSI-based VM and attached to an NVMe-based VM. Once attached, the disk type will automatically convert to NVMe.

Older Azure VM types (such as Ebsv6) attach all disks to a single NVMe controller. Select newer VM sizes (V7 and above, running on Intel and ARM hardware) automatically distribute disks across multiple controllers and separate cached disks (including the OS disk) and uncached data disks for improved performance and reliability.

Boot and cached data disks are assigned to the cached controller and uncached data disks go to the uncached controller. Controller assignment is automatic based on disk caching policy selected in the VM settings.

If you need to change the caching policy of a disk, it is recommended to stop the VM, change the caching policy, and then start the VM again for stable operation. This helps avoid inconsistent states or remapping issues. OS disk caching changes are non-functional and will be disabled in future updates.