Microsoft has announced the general availability (GA) of Standard SSD and Premium SSD support for Azure Ephemeral OS Disks. Previously, only Standard HDD could be selected as the base disk type; with this significant upgrade for stateless workloads, customers will see improved performance and reliability.
As a bit of background, Azure Ephemeral OS Disks are designed for stateless virtual machines where the OS disk is local to the VM and not persisted to Azure Storage. They can be helpful for rapid deployment and re-imaging but the ephemeral nature means data is lost on re-imaging or VM deallocation.
It’s not just faster hardware that users benefit from after this announcement. Microsoft says that its Premium SSDs offer a 99.9% service-level agreement, compared to 95% for the Standard HDD, meaning customers get better uptime and reliability.
Not only that, but Microsoft says its Premium SSDs provide 8-10 times higher IOPS than Standard HDD. Some specific benefits you’ll see when using SSDs is faster scaling and VM reliability, quick deployment of fresh desktops, and faster job starts on clean environments.
In terms of cost, the Standard HDD as base disk for Ephemeral OS disks remains free of additional storage costs. If you choose the Standard SSD or Premium SSD as the base disk then you will face additional disk costs.
To get started with an SSD, you need to select it as the base disk type during virtual machine creation via Azure CLI, PowerShell, or ARM templates. To create a VM with Ephemeral OS disk & Premium SSD base disk you can use the following AzCLI command:
az vm create --name MyVM --resource-group MyRG --image UbuntuLTS --ephemeral-os-disk true --storage-sku Premium_LRS
Or this PowerShell command:
Set-AzVMOSDisk -VM $VirtualMachine -DiffDiskSetting Local -DiffDiskPlacement ResourceDisk -CreateOption FromImage -Caching ReadOnly -StorageAccountType "Premium_LRS"
You can also choose SSDs through the Azure Portal by selecting the Ephemeral OS disk option and choosing Premium SSD in OS Disk Type. To learn more check out the Ephemeral OS disks Learn page.
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