Generally Available: SSD storage account support for Ephemeral OS disks

We’re excited to announce the General Availability (GA) of SSD storage account support for Ephemeral OS Disks during creation of VM/VMSS. This milestone builds on the momentum from our public preview and brings enhanced performance, and reliability to your stateless workloads. This feature is particularly beneficial for stateless applications where VM boot times and reliability are important. The improved read performance from an SSD base disk accelerates boot and application initialization times. Some specific examples include:

• Containerized workloads: Achieve faster scaling operations and higher VM reliability
• Virtual Desktop Infrastructure (VDI): Rapidly deploy fresh desktops for users in pooled environments.
• CI/CD build agents: Start jobs faster on clean, consistent environments.

What’s New?

With this GA release, customers can now choose Standard SSD (StandardSSD_LRS) or Premium SSD (Premium_LRS) as the base disk type for Ephemeral OS Disks; previously limited to Standard HDD. This unlocks:

1. Higher SLA: VMs using Premium SSDs benefit from a 99.9% SLA, compared to 95% with Standard HDD.
2. Improved Read Performance: By choosing Premium SSD as the base disk, customers can enhance the disk read performance of their OS disks. While most writes occur on the local temp disk, some reads are performed from managed disks. Premium SSD disks provide 8-10 times higher IOPS than Standard HDD.

How It Works?

Ephemeral OS disks are split into 2 disks - a diff disk on local temp disk and a base disk using managed disks. All writes to existing and new files occur on the diff disk, while the original files are read from the base disk. Both the diff disk and the base disk are crucial for the VM's operation.

SSD support is a new option that allows customers to choose the type of base disk that is used for the ephemeral OS disk. Previously, the base disk could only be Standard HDD. Now, customers can choose between the three types of disks: Standard HDD(Standard_LRS), Standard SSD (StandardSSD_LRS) or Premium SSD (Premium_LRS). By using SSD as the base disk, customers will achieve higher SLA and better performance compared to Standard HDD. Standard HDD as base disk will continue to be free to use with Ephemeral OS disk. However, customers will incur additional disk cost for provisioning SSD as the base disk.

How to use?

With SSD support, customers can now specify the base disk type during VM creation using Azure CLI, PowerShell, or ARM templates. For example, to create a VM with Ephemeral OS disk & Premium SSD base disk, customers can use the following command:

AzCLI

az vm create --name MyVM --resource-group MyRG --image UbuntuLTS --ephemeral-os-disk true --storage-sku Premium_LRS

PowerShell

Set-AzVMOSDisk -VM $VirtualMachine -DiffDiskSetting Local -DiffDiskPlacement ResourceDisk -CreateOption FromImage  -Caching ReadOnly -StorageAccountType "Premium_LRS"

Get Started Today

You can start deploying VMs with Ephemeral OS disks using Azure Storage today through the Azure Portal, CLI, PowerShell, and ARM templates. When creating a VM, select the option to use an Ephemeral OS disk and choose Premium SSD in OS Disk Type.

For more detailed information and deployment steps, please refer to our official documentation on Ephemeral OS disks.

We look forward to seeing how you leverage the expanded capabilities of Ephemeral OS disks in your Azure environment.