Hetzner Live Migration Demos: A Step‑by‑Step Guide

Introduction

Moving a running server without downtime sounds like magic – and with Hetzner’s Live Migration feature, it’s a reality. In this demo‑focused guide we walk you through the entire process, from preparation to validation, so you can migrate VMs safely and confidently.

What Is Live Migration?

Live migration copies a virtual machine’s memory, CPU state, and attached storage to a new host while the VM stays online. Hetzner’s implementation runs on the Cloud and Dedicated Root Server platforms, offering:

• Zero‑downtime for most workloads.
• Automatic network re‑attachment.
• Rollback options if something goes wrong.

Prerequisites

Technical Requirements

• Hetzner Cloud account with at least two servers in the same data centre.
• Root access (or sudo) on the source VM.
• SSH key pair for secure communication.

Best‑Practice Checklist

1. Backup critical data – snapshots or external backups.
2. Update the OS and kernel to the latest stable version.
3. Disable SELinux/AppArmor temporarily if they interfere with migration.
4. Ensure both servers have identical CPU architectures (e.g., x86_64).

Demo 1: Simple Live Migration Using the Hetzner Cloud Console

Step 1 – Create the Target Server

Log in to the Hetzner Cloud Console, select the same data centre, and spin up a new server (same size is recommended). Note the SERVER_ID of both source and target.

Step 2 – Install the Migration Helper

ssh root@source-server apt-get update && apt-get install -y qemu-guest-agent systemctl enable --now qemu-guest-agent 

Repeat on the target server.

Step 3 – Trigger Migration

# Replace IDs with your own hcloud server migrate --source SERVER_ID --target TARGET_ID 

The console shows progress: copying memory, syncing disks, and final switchover.

Step 4 – Verify

• Check uptime – it should show continuous operation.
• Run ping or curl to confirm services are reachable.

If everything looks good, you can decommission the old server.

Demo 2: Live Migration via API (Advanced)

Why Use the API?

The API allows automation, bulk migrations, and integration with CI/CD pipelines. It’s perfect for teams managing dozens of VMs.

Step‑by‑Step

# Set your API token export HCLOUD_TOKEN="your-token" # Get server IDs SOURCE=$(hcloud server list --output json | jq -r '.[] | select(.name=="source-vm") | .id') TARGET=$(hcloud server create --name target-vm --type cx31 --datacenter nbg1-dc3 --output json | jq -r '.server.id') # Initiate migration hcloud server migrate $SOURCE $TARGET 

The command returns a action_id. Poll the action until it’s "finished":

while true; do   STATUS=$(hcloud action get $action_id --output json | jq -r '.status')   [ "$STATUS" = "running" ] && sleep 5 || break done 

Post‑Migration Checks

Run a quick health‑check script on the target:

#!/bin/bash services=(nginx mysql php-fpm) for svc in "${services[@]}"; do   systemctl is-active --quiet $svc && echo "$svc OK" || echo "$svc FAILED" done 

Common Issues & Troubleshooting

• Network timeout – Verify both servers share the same VPC and firewall rules.
• Incompatible CPU features – Use the "migrate‑compatible" server type or enable cpu-model flag.
• Disk sync failure – Ensure no heavy write load during migration; consider snapshotting first.

FAQ

Is live migration supported for Windows VMs?

Yes, but you must enable Hyper‑V integration services and use a supported Windows Server edition.

How long does a migration take?

Typical migrations finish in 2–5 minutes for a 20 GB VM. Larger memory footprints may take longer.

Can I roll back if something goes wrong?

Hetzner keeps the source VM running in a paused state until you confirm success. You can abort and revert instantly.

Do I need to stop services?

No, live migration is designed to keep services running, though it’s wise to quiesce databases for consistency.

Conclusion

Hetzner’s live migration feature removes the traditional hassle of server moves. Whether you prefer the graphical console or the powerful API, the steps above give you a reliable roadmap. Test the process in a non‑critical environment, follow the checklist, and you’ll enjoy seamless scaling and maintenance without compromising uptime.

Call to Action

Ready to try a live migration on your Hetzner cloud? Create a test server now and follow the demos. Need help? Contact our support team for a personalized walkthrough.