You took a snapshot of your home server before an update, so you feel safe. Then the disk dies, and the snapshot dies with it. That is the core of snapshot vs backup. A snapshot is a quick undo point that lives on the same storage as the original. A backup is a separate, complete copy you can restore somewhere else. You need both, and you only know a backup works after you restore it once.
Who this is for: you run a home server, a NAS or a Proxmox box with things you care about, such as family photos, a password vault or a smart home setup. Who it is not for: you only run throwaway test machines that you can rebuild in ten minutes. You can still read on, but you need less of it.
What a snapshot is
A snapshot freezes the state of a virtual machine (VM) or a disk at one moment. After that, the system writes new changes to a separate layer. If an update goes wrong, you roll back, and the VM returns to the frozen state, usually quickly. A rollback also throws away everything written since the snapshot, such as new photos or passwords. Save or back up recent changes before you roll back.
Proxmox can snapshot both VMs and containers, if the storage supports it. The guide to containers vs virtual machines explains the two. Snapshots are great for one job: a short-term undo button before a risky change. Take one before an upgrade. Test the upgrade. Then delete the snapshot when you are happy.
What a backup is
A backup is a full, independent copy of your data, stored somewhere else. It does not need the original disk to exist. If the server burns, you can restore the backup onto new hardware.
In Proxmox VE, the docs say plainly that its backups "are always full backups", with the VM or container configuration and all data. See the Proxmox VE backup and restore docs. Tools such as Proxmox Backup Server then store those backups in a smart way, so later runs only send what changed.
Snapshot vs backup: four reasons a snapshot is not a backup
- It lives on the same storage. A snapshot sits on the same disk or storage pool as the VM. If that disk fails, you lose the VM and every snapshot at once.
- It depends on the original. Most snapshots store only the changes since the freeze. They are not a complete copy, so they mean nothing without the original disk.
- It shares the same mistakes. Delete the VM by accident, and its snapshots usually go too. Ransomware (malware that locks your files and asks for money) that reaches the host can reach the snapshots too.
- It is not off-site and not long-term. Snapshots stay in the house, on the box. Old snapshots also grow as data changes, and they can slow the VM and fill the disk.
One more trap. An older Proxmox wiki page on live snapshots notes that "snapshots are not included in the backup", and current backup logs still report snapshots as not included. So a backup does not save your snapshot history either. Treat the two as separate tools.
A word on naming: Proxmox has a backup mode called "snapshot mode". It is still a real backup. The name only means the backup runs while the VM keeps working, so you have little downtime.
| Question | Snapshot | Backup |
|---|---|---|
| Where does it live? | Same storage as the VM | Separate storage, ideally another box and another place |
| Is it a complete copy? | Usually no, it records changes | Yes |
| Survives a dead disk? | No | Yes, if stored elsewhere |
| Best use | Undo before an update | Recover from loss, theft, fire or ransomware |
| How long to keep | Hours or days | Weeks, months or longer, by a plan |
The 3-2-1 backup rule, in plain words
The US Cybersecurity and Infrastructure Security Agency (CISA) gives a simple rule. On its guide to backing up business data, it says to keep:
- 3 copies of important files,
- on 2 different types of storage (like a hard drive and the cloud),
- with 1 copy stored off-site, away from your home or business.
For a home server, that can look like this. The live data sits on the server. A backup sits on a second box or a USB drive at home. A third copy sits off-site, such as a drive at a relative's house or an encrypted cloud copy. CISA also tells you to test your backups, make sure you can restore data fully and partly, and be able to roll back at least seven days. That test is the part most people skip.
Some app makers say the same. The Immich photo project's own README warns you to always follow a 3-2-1 backup plan for your photos and videos. If you followed the guide to self hosting in 2026, this is the step that makes it safe.
What you need for a first restore drill
- Hardware: your server, plus a separate place for backups. A second small box, a NAS or an external drive all work. Do not count a second folder on the same disk.
- Software: any backup tool that can restore. This guide uses Proxmox VE with Proxmox Backup Server as the worked example. On Synology, Unraid or TrueNAS, use the same drill: restore to a new location, never over the original, then check your marker.
- Skill: you can click through the Proxmox web page and start a VM.
- Time: set aside an evening. A small test VM restores faster than a big one.
- Cost: Proxmox Backup Server is free and open source (AGPLv3), per its official introduction. Optional paid subscriptions exist for support and the enterprise update channel. Your real cost is the backup disk or second box. Check current terms on the Proxmox site, as of October 2026.
Proxmox Backup Server stores incremental, deduplicated backups (it skips data it already has), can encrypt them on your side before they leave the host, and checks them with checksums. It can also run "verify jobs" on a schedule to catch damaged backup data. It is new to many home users, so read its docs before you trust it with irreplaceable files. For the bigger picture of where this box fits, see the home server setup guide.
How to test a backup restore: a step-by-step drill
The goal is simple. Prove that a real backup turns back into a working machine, without touching the live one.
- Pick a test subject. Choose one VM or container that matters but is small. A password vault or a photo app is a good choice.
- Plant a marker. Create a small text file inside it, or note one recent photo or record. You will look for it after the restore.
- Run a backup now. In Proxmox VE, open the VM, go to Backup, and choose "Backup now" to your Proxmox Backup Server storage. Wait for the task to finish with no errors.
- Verify the backup. On Proxmox Backup Server, run a verify on that backup, or check that your scheduled verify job passed.
- Restore to a new ID. In Proxmox VE, open your backup storage, select the backup and choose Restore. Give it a new, unused VM ID, so you never overwrite the live VM. Check "Unique" so the copy gets new network hardware (MAC) addresses. Leave "Start after restore" unchecked.
- Keep it off the network. Before you start the copy, open its Hardware tab and disconnect its network card. Two copies of the same server on one network can clash. In Options, also turn off "Start at boot", or the copy may start with the host after a reboot.
- Start it and check it. Boot the restored VM. Log in from the console. Find your marker file or record. Open the app if you can.
- Try a single-file restore. On the backup storage, use the "File Restore" button to browse inside the backup and download one file. This is the restore you will need most often.
- Write down the results. Record the date, what you restored, how long it took and any problem.
- Clean up. Delete the test VM when you are done, so it does not run by mistake later.
If you prefer the command line, Proxmox VE also restores with qmrestore for VMs and pct restore for containers. Both accept a new ID. Check the docs for the exact options on your version.
The risky bit: how restore drills go wrong
- Restoring over the live VM. Always use a new VM ID for a drill. One wrong click on the original ID replaces your live machine with an older copy.
- Two servers, one network. A restored copy can grab the same IP address or talk to the same devices. Keep it disconnected.
- Backups on the same disk. A "backup" stored next to the original fails with it. Move it to another device.
- Lost encryption key. If you encrypt backups and lose the key, nobody can restore them. Store the key in at least two safe places, away from the server.
- Snapshots left running. A forgotten snapshot keeps growing and can fill the disk. Delete snapshots once an update proves fine.
- No off-site copy. Fire, flood and theft take every device in the house. Proxmox Backup Server can sync to a second Proxmox Backup Server (a "remote") with a sync job, which is one way to get a copy off-site.
The recovery step: make the drill a habit
One drill proves today's backup. It does not prove next month's. Put a reminder in your calendar and repeat the drill on a schedule. Rotate which VM you test. After any big change (new disk, new backup target, major upgrade), run a drill again. The guide to what Proxmox VE is covers the platform itself if you are still choosing.
Printable restore drill checklist
- I have 3 copies of my important data, on 2 types of storage, with 1 off-site.
- No backup lives on the same disk as the data it protects.
- Backup jobs ran without errors this week.
- A verify job checked the backups recently.
- I restored one VM or container to a new ID and it booted.
- I found my marker file inside the restored copy.
- I restored one single file from a backup.
- My encryption key is stored in two safe places off the server.
- No old snapshots are left over from past updates.
- I wrote down the date, the time it took and any problems.
- The next drill is in my calendar.
FAQ
Is a snapshot a backup?
No. A snapshot is a short-term undo point on the same storage as the original. If that storage fails, the snapshot is gone too. A backup is a separate, complete copy you can restore elsewhere.
Should I use snapshots or backups?
Use both, for different jobs. Take a snapshot right before an update so you can roll back fast. Keep scheduled backups on another device, with one copy off-site, for real disasters.
What is the 3-2-1 backup rule?
Keep 3 copies of important files, on 2 different types of storage, with 1 copy off-site. CISA recommends it for small businesses, and it works well for a home server too.
How often should I test a backup restore?
Test on a regular schedule, and after any big change to your server or backup setup. Pick a rhythm you will keep, and put it in your calendar. A small, regular drill beats a big one you never do.
Can Proxmox Backup Server restore a single file?
Yes. In Proxmox VE, the File Restore button on the backup storage lets you browse a backup stored on Proxmox Backup Server and download single files. Check the docs for your version.
Does a Proxmox backup include my snapshots?
No. Proxmox backups do not include snapshots, and the backup log says so when it finds them. The backup holds the VM's current state and configuration, not its snapshot history.
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