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Proxmox Backups (PBS) FAQ

Backup​

What can I back up with PBS?​

Three source types are supported:

  • QEMU VMs (vm): Proxmox VE virtual machines — configuration + disk image(s)
  • LXC containers (ct): filesystem tree + configuration
  • Linux servers (host): directories and files via the proxmox-backup-client, without needing Proxmox VE

Are backups incremental?​

Yes. PBS only transfers modified chunks since the last backup. A 100 GB VM may only generate a few hundred MB of network traffic on subsequent backups.

Does backup stop the VM?​

No, in Snapshot mode (recommended). Proxmox VE creates a temporary VM snapshot without stopping it. suspend and stop modes are also available but cause downtime.

Can I back up from multiple Proxmox VE clusters?​

Yes. Use a different namespace per cluster to avoid overlapping VMID conflicts. Each cluster can have its own access token limited to its namespace.

Deduplication​

Is deduplication automatic?​

Yes. PBS deduplicates chunks on the fly, with no special configuration. Identical blocks are stored only once, even across different VMs.

What deduplication rate can I expect?​

CaseTypical rate
VMs cloned from the same template70 – 90%
Varied production environment50 – 70%
Highly varied data (databases)20 – 40%

The current ratio is visible in the dashboard (e.g. 6.42×).

Do I need to run GC to benefit from deduplication?​

No. Deduplication is active at all times during backups. Garbage Collection (GC) frees space from orphan chunks after a prune — they are two distinct mechanisms.

Retention and deletion​

What is the difference between Prune and Garbage Collection?​

OperationWhat it doesFrees space?
PruneRemoves old snapshot metadataNo
Garbage CollectionRemoves actual orphan chunksYes

You need to run prune then GC (at least 1 hour apart) to reclaim space.

Why doesn't GC free space immediately?​

PBS applies a 24h05 grace period before deleting chunks. This is tied to the Linux filesystem relatime behavior: atime is only updated if the last access was more than 24h ago. This safety prevents deleting chunks still being used by an active backup job.

Does prune permanently delete data?​

Yes and no. Prune removes the snapshot metadata. The data is still physically present until the next GC run. To ensure sensitive data is erased, prune the relevant snapshots then run GC.

Restore​

Can I restore a single file without restoring the entire VM?​

Yes. PBS supports granular restore:

  • a specific file or directory
  • a particular disk volume
  • a full VM

From the Proxmox VE interface → Backup → snapshot → Restore, you can target the desired level.

Can I restore to a different machine?​

Yes. As long as the target machine is connected to the PBS datastore with the correct credentials, you can restore any snapshot to any Proxmox VE host.

Access and security​

Do I need a fingerprint to connect?​

No. The HostMyServers PBS service uses a TLS certificate signed by a recognized CA. No fingerprint is required when adding the storage in Proxmox VE.

Should I use a PBS user or an API token?​

Prefer an API token for automated connections (Proxmox VE, scripts). A token:

  • can be revoked individually without changing a password
  • can have permissions reduced to the strict minimum
  • is identified in the format user@pbs!token-name

Is client-side encryption supported?​

Yes. PBS supports client-side encryption — data is encrypted before transfer, with a key you manage. HostMyServers does not have access to your encryption keys. Key management is your responsibility (secure backup of the key is essential for restore).

Capacity and upgrades​

Can I upgrade my capacity without downtime?​

Yes. Capacity upgrades are done from the client portal without recreating the datastore, with no data loss and no interruption. See Upgrading capacity.

What capacity should I start with?​

Estimate: gross VM volume × number of snapshots to keep × (1 - estimated deduplication rate). For your first order, leave a comfortable margin — you can always increase later.

Network​

On which port is PBS accessible?​

The PBS server listens on HTTPS port 8007. This port must be reachable from your Proxmox VE nodes to the PBS endpoint.

Can I back up a Linux server without Proxmox VE?​

Yes, via the proxmox-backup-client. It backs up directories or volumes from any Linux server (physical or virtual) with network access to port 8007 of the datastore.