The default vzdump backup built into Proxmox VE works, but it re-copies the full VM disk every single run — slow, and wasteful of storage when most of a 100GB disk hasn’t changed since yesterday. Proxmox Backup Server (PBS) is a separate, free product built specifically to fix that: it breaks disk images into content-addressed chunks, so unchanged data is never stored or transferred twice.

How the Chunk Store Works

Concept	What it means
Chunking	Each VM disk is split into variable-sized chunks based on content, not fixed offsets
Content addressing	Each chunk is stored once, named by its own checksum — identical chunks across VMs or backup runs are only stored once, server-wide
Incremental sync	A new backup run only needs to upload chunks that don’t already exist in the datastore
Compression	Chunks are compressed with Zstandard before storage, on top of the deduplication savings

In practice this means the first backup of a VM takes roughly as long as a normal full backup, but every backup after that is often a fraction of the time and space — because most of a running VM’s disk doesn’t change day to day.

Step 1: Set Up the PBS Datastore

# On the Proxmox Backup Server
proxmox-backup-manager datastore create vm-backups /mnt/backup-disk
proxmox-backup-manager user create backup@pbs --password

Step 2: Add PBS as Storage in Proxmox VE

Datacenter > Storage > Add > Proxmox Backup Server
  Server: pbs.example.com
  Datastore: vm-backups
  Username: backup@pbs
  Fingerprint: (shown on the PBS server's dashboard)

Step 3: Schedule Backup Jobs

Datacenter > Backup > Add
  Storage: vm-backups (PBS)
  Schedule: daily 02:00
  Mode: snapshot
  Retention: keep-daily=7, keep-weekly=4, keep-monthly=6

PBS’s retention (“prune”) settings work on top of the deduplicated store — keeping 30 daily snapshots of a VM doesn’t cost 30x the disk space, because most chunks are shared across those snapshots.

Restoring Without a Full VM Restore

PBS’s file-level restore lets you mount a specific backup snapshot and browse or download individual files — useful when someone needs one accidentally-deleted file back, not the whole VM rolled back to yesterday:

proxmox-backup-client restore vm/101/2026-09-16T02:00:00Z drive-scsi0.img.fidx /mnt/restore --repository backup@pbs@pbs.example.com:vm-backups

PBS vs vzdump-Only Backups

	vzdump to local/NFS storage	Proxmox Backup Server
Space usage over time	Grows linearly with each full backup	Grows mainly with actual data changes
Backup speed after the first run	Same every time	Much faster — only new chunks transfer
File-level restore	Not built in	Native, without restoring the whole VM
Setup effort	None — built into Proxmox VE	Requires a separate PBS instance (can be a VM itself, ideally on separate hardware)

Conclusion

Proxmox Backup Server turns backup storage from “however many terabytes times however many days you keep” into something closer to “how much data actually changes.” It costs a bit of setup — a separate datastore and, ideally, separate hardware from what it’s backing up — but for any environment doing daily VM backups it pays for itself in storage and backup-window time within the first week.