Hot off the press is Proxmox Backup Server 4.0. PBS is a great tool to use with your Proxmox VE servers to do fast and easy backups of your VMs and LXCs. It’s very easy to setup, and can be deployed in a variety of forms: bare metal, VM or LXC. 

Personally, I’ve deployed Proxmox Backup Server 4.0 as a VM on my primary Synology NAS. This PBS instance covers both of my Proxmox hosts, so I can back up all VMs and LXCs to one central server not hosted on any Proxmox VE servers.

The VM deployment is also the most flexible in terms of supporting a local virtual disk, iSCSI LUNs, NFS and S3 datastores. My PBS server uses VM-provisioned virtual disk for local storage, and an iSCSI LUN off a secondary local Synology NAS as a secondary datastore. 

Core Platform Updates

Debian 13 “Trixie” Foundation

• Updated to Debian 13 “Trixie” with Linux kernel 6.14
• Includes ZFS 2.3.3 for improved storage capabilities
• Enhanced hardware compatibility and security improvements

Major New Features

S3-Compatible Object Storage Support (Tech Preview)

• Native support for S3-compatible object storage as backend for backups
• Maintains a local cache to reduce repeated API calls and improve read performance
• Requires 64-128 GiB local cache for optimal performance
• Works with various S3 providers (AWS, Backblaze, Wasabi, etc.)

Live RAIDZ Expansion

• ZFS 2.3.3 now allows to expand existing RAIDZ pools with minimal downtime
• Users can now add new disks to an existing RAIDZ pool without downtime
• Addresses a longstanding ZFS limitation

Automatic Sync Jobs for Removable Datastores

• Users can now configure sync jobs to run automatically each time a relevant removable datastore is mounted
• New “run-on-mount” flag on sync jobs
• Simplifies datastore synchronization, especially in labs, field work, or air-gapped setups

Additional Improvements

Web Interface Enhancements

• Fixes for datastore creation tasks not displaying properly
• General UI polish and quality of life improvements

Integration and Compatibility

• Proxmox Backup Server seamlessly integrates into Proxmox Virtual Environment
• Supported upgrade path from Proxmox Backup Server 3.x to 4.0
• Upgrade helper tool pbs3to4 available

Proxmox Backup Server 3.x to 4.0 Upgrades

If you are currently running Proxmox Backup Server 3.x and want to upgrade to 4.0, check out their official upgrade guide:

Upgrade from v3 to v4 – Proxmox Backup Server

I ran through the procedure without issue and it was pretty quick. Just make sure your PBS 3.x server is freshly updated to be at least 3.4.2-1 or later. 

Summary

Proxmox Backup Server 4.0 is an incremental update for most home users over the prior 3.x version. The neatest new feature is supporting S3 object storage targets. This feature is only in tech preview, and I’ve seen some issues. So it’s great to experiment with, but not ready for prime time.