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Ephemeral OS Disk in limited preview

Posted on October 4, 2018

Program Manager, Azure Compute

Last week at Microsoft Ignite, we launched Ultra SSD, a new industry leading high-performance disk type for IO intensive workloads. Adding to that, today we are delighted to share the limited preview of Ephemeral OS Disk, a new type of OS disk created directly on the host node, providing local disk performance and faster boot/reset time.

Ephemeral OS Disk is supported for all virtual machines (VM) and virtual machine scale sets (VMSS). This offering is based on your feedback to provide a lower cost, higher performant OS disk for stateless applications, which enable them to quickly deploy the VMs and reset them to its original state.

Ephemeral OS Disk is ideal for stateless workloads that require consistent read/write latency to OS disk, as well as frequent reimage operations to reset the VM(s) to the original state. This includes workloads such as website applications, game server hosting services, VM pools, computation, jobs and more. Ephemeral OS Disk also works well for workloads that are leveraging low-priority VM scale sets.

Key comparisons between Persistent OS disk and Ephemeral OS disk

  Persistent OS Disk Ephemeral OS Disk
Size limit for OS disk 2 TiB

Up to 30 GiB for preview

Up to VM cache size at general availability

VM sizes supported All DSv1, DSv2, DSv3, Esv2, Fs, FsV2, GS
Disk type support Managed and unmanaged OS disk Managed OS disk only
Region support All regions All regions excluding sovereign clouds
Specialized OS disk support Yes No
Data persistence OS disk data written to OS disk are stored in Azure Storage OS disk data is stored to local host machine and is not persisted to Azure Storage
Stop-deallocated state VMSS instances and VMs can be stop-deallocated and restarted from the stop-deallocated state VMSS instances and VMs cannot be stop-deallocated
OS disk resize Supported during VM creation and after VM is stop-deallocated Supported during VM creation only
Resizing to a new VM size OS disk data is preserved OS disk data is deleted, OS is re-provisioned

How to join preview

To enroll in the limited public preview, you will need to submit this form and your subscription will be approved within 24 to 48 hours starting October 10, 2018. You can check the status of your request by running the following PowerShell command:

Get-AzureRmProviderFeature -FeatureName localdiffdiskpreview -ProviderNamespace Microsoft.Compute

We would love to get your feedback via Microsoft Teams or email EphemeralOSDiskvTeam@microsoft.com.