What is Proxmox Backup Server (PBS)?

Proxmox Backup Server as a managed service - WZ-IT designs, builds and operates your PBS environment: deduplicated, encrypted, with offsite protection and documented restore tests. Book a call · More on Proxmox Backup Server

Proxmox Backup Server (PBS) is an open-source backup solution from Proxmox Server Solutions GmbH, built specifically to protect Proxmox VE environments. PBS backs up virtual machines, LXC containers and physical hosts incrementally, deduplicated and encrypted, which significantly reduces both storage usage and network load. The software is licensed under the GNU AGPLv3 and is fully free to use; an optional subscription provides the stable enterprise repository and vendor support.

PBS is designed as a standalone system. It runs on its own Debian-based machine and talks to the systems it protects over an efficient client-server protocol. That makes it far more than a script that copies disk images: PBS is a central backup platform with its own data store, integrity checking and access control.

What Proxmox Backup Server actually does

PBS acts as the central backup server for one or many Proxmox VE instances. Backups land in a so-called datastore, which can sit on local disk, on ZFS, on attached storage, or since version 4 on S3-compatible object storage.

The connection follows a client-server model:

• Proxmox VE talks to PBS natively. You add the backup server as a storage target and back up VMs and containers directly from the web interface or on a schedule.
• The proxmox-backup-client additionally backs up physical Linux hosts as well as individual directories and file systems.
• Management, monitoring and restore all run through the web interface, a REST API and the command line.

Restores are granular: an entire VM, a single container, individual files from a backup, or a full bare-metal restore.

Is Proxmox Backup Server free?

Yes. PBS is fully licensed under the GNU AGPLv3. There is no feature gating, no limit on the number of VMs, clients or datastores, and no storage cap. The difference between free and paid use lies in the repository and support, not in the feature set:

• Without a subscription you use the no-subscription repository with current, but less heavily tested updates.
• With a subscription you get the enterprise repository with especially stable packages plus vendor support.

The subscription is billed per server and year and includes unlimited backup storage and unlimited backup clients. The official tiers (as of June 2026):

For the full picture of Proxmox VE and PBS costs, see How much does Proxmox cost?.

The core features at a glance

PBS differs from simple backup scripts through a set of features that together make up a dependable enterprise backup:

• Incremental ("incremental forever"): after the first full backup, PBS transfers only changed data blocks. For running VMs a dirty bitmap tracks the changes, which makes daily backups very fast.
• Deduplication: data is split into chunks identified by their SHA-256 hash. Identical blocks are stored only once across all VMs and snapshots in a datastore. This is the single biggest lever on storage usage.
• Compression: chunks are additionally compressed with Zstandard, saving space and transfer time.
• Client-side encryption: AES-256 in GCM mode, performed on the client. The key stays on the client and the server only stores encrypted chunks. Our guide on encrypted offsite backups at Hetzner goes into the details.
• Verify jobs: PBS checks stored backups for integrity on a schedule, catching silent data corruption (bit rot) before it surfaces in a real recovery.
• Pruning and garbage collection: a retention policy (keep-last, keep-daily, keep-weekly, keep-monthly, keep-yearly) marks old snapshots for removal. Garbage collection then frees the storage by removing chunks that are no longer referenced.
• Tape backup (LTO): for air-gapped and long-term archiving, PBS writes backups to LTO tape, including label and tape-library management.
• Remote sync and S3: datastores can be synchronized between PBS instances. Since version 4, PBS also supports S3-compatible object storage as a backend, officially in version 4.2 and with parallel sync jobs.

PBS vs. vzdump: where is the difference?

Proxmox VE ships its own backup tool, vzdump. It produces a full archive per VM or container on each run and works well for simple, occasional backups. As soon as storage efficiency, long retention and provable integrity matter, PBS shows its strengths.

vzdump stays useful for one-off backups or setups without a dedicated backup server. For business operations with multiple hosts, PBS is the clear standard.

Backup strategies for businesses

A backup server alone is not a strategy. The proven baseline is the 3-2-1 rule: at least 3 copies of the data on 2 different media, 1 of them at a different location. PBS covers this cleanly in technical terms:

• A local datastore for fast, frequent day-to-day restores.
• An offsite copy via a second PBS or an S3 backend at a separate location. From a ransomware perspective the pull direction is decisive: the external server pulls the data and is not reachable from the source. Our how-to on the offsite pull architecture with PBS explains exactly how this works.
• Immutability against encryption malware via S3 Object Lock, tape or removable datastores.
• Restore tests: a backup that has never been restored is only an assumption. Regular, documented restore tests belong in any robust strategy and are effectively mandatory in a NIS2 context.

Current version: Proxmox Backup Server 4.2

The current release is Proxmox Backup Server 4.2, published on 29 April 2026. It is based on Debian 13.4 (Trixie), uses Linux kernel 7.0 as the new default and ships ZFS 2.4. The main highlights:

• S3-compatible object storage is now officially supported as a backend.
• Parallel sync jobs via worker threads increase throughput, especially over high-latency networks.
• Encrypted sync allows snapshots to be encrypted and decrypted on push and pull sync.
• Namespace management lets administrators move backup groups and namespaces within a datastore.

Operations and support

A backup is only worth something when the restore works when it counts. That is exactly where we come in: WZ-IT designs, builds and operates Proxmox Backup Server environments with deduplication, client-side encryption, offsite pull protection and regular, documented restore tests. Learn more on our page about Proxmox Backup Server as a managed service, or talk to us directly in a free initial consultation.