We’re excited to announce the public preview of hibernated virtual machines in standby pools for Azure Virtual Machine Scale Sets (VMSS)—a new capability designed to reduce scale-out latency while optimizing cost and resource efficiency.
Why Hibernated Standby Pools?
Standby pools for Virtual Machine Scale Sets allow you to pre-provision virtual machines that are ready to be pulled into your scale set when demand spikes. Until now, these VMs could be kept in either a running or deallocated state. With this public preview, you can now maintain VMs in a hibernated state—preserving memory and OS state while avoiding compute charges.
This is especially valuable for workloads that require fast startup times but don’t need to be continuously running, such as:
- Session-based applications
- Stateful services
- Burstable compute tasks
How It Works
When you configure a standby pool with the hibernated VM state:
- VMs complete all post-provisioning steps (OS provisioning, extension installs, etc.) before entering hibernation.
- During a scale-out event, the VMs are moved into the scale set and resumed—significantly reducing time-to-serve.
- VMSS only pulls VMs that are in the goal state (i.e., fully hibernated and ready). If none are available, it falls back to provisioning new VMs.
Requirements
To use hibernated standby pools:
- Your VMSS profile must have hibernationEnabled = true.
- The instances must be fully eligible and configured to support hibernation. For more information, see the Azure VM hibernation documentation.
Benefits
- Faster scale-out
- Cost savings
- Operational simplicity
Get Started
For more information, check out Standby pools for Virtual Machine Scale Sets
Updated May 14, 2025
Version 1.0
micahmckittrick
Microsoft
Microsoft