ephemeral-os-disk

name	ephemeral-os-disk
description	Use local-SSD-backed ephemeral OS disks for stateless workloads

Ephemeral Os Disk

When to use this skill

• AKS nodes, stateless web/API tiers, CI runners

Key concepts

• OS disk lives on the host's local SSD (or cache) — no storage account charges, faster reimage.
• Data is lost on host failure, redeploy, or stop-deallocate.
• Placement options: CacheDisk (default), ResourceDisk, NvmeDisk (newer SKUs).
• Size capped by host cache/temp disk size — check SKU.

Azure CLI examples

az vm create ... --ephemeral-os-disk true --ephemeral-os-disk-placement ResourceDisk

Common pitfalls

• Storing state on the OS disk — gone on any host event.
• Picking a SKU whose cache/temp disk is too small for the image.

References

• Microsoft Learn: search for "Ephemeral Os Disk Azure VM" on https://learn.microsoft.com

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