Proxmox Backup Server 3.4 Adds Faster Garbage Collection and Smarter Sync Filters

Proxmox Backup Server 3.4 is now available. It brings a range of technical refinements to improve performance, flexibility, and integration with off-site storage workflows.

Proxmox Backup Server 3.4 Main Enhancements

This release highlights a more efficient garbage collection (GC) process. Cleaning up unused data chunks can become a performance bottleneck in systems where backups are deduplicated. With version 3.4, Proxmox has added a caching mechanism to this process, significantly reducing the number of disk metadata writes needed during GC runs. The result is faster cleanup with a trade-off of slightly increased memory use. Admins can also tweak the caching behavior on a per-datastore basis, offering more control over memory and performance trade-offs.

Syncing backups across remote sites has also become more granular. While it was already possible to define which backup groups should be synced, Proxmox Backup Server now allows filtering based on backup status—specifically, whether snapshots are encrypted or verified. This makes building automated sync workflows that comply with security or integrity requirements, especially in off-site or multi-site configurations easier.

For environments that rely on tape storage, version 3.4 introduces the ability to scale up the number of worker threads when reading chunks. Depending on the setup, this can improve throughput and speed up large tape backups—something that might benefit users with significant long-term storage needs.

Another helpful upgrade is a statically linked version of the Proxmox Backup command-line client. This change simplifies running file-level backups on Linux systems outside the Proxmox Virtual Environment. The new binary is portable and doesn’t require shared libraries, making it easier to drop into different systems and environments.

The platform continues to keep pace with open-source infrastructure updates. Built on Debian 12.10 (“Bookworm”), Proxmox Backup Server 3.4 runs on Linux kernel 6.8.12-9 by default, with kernel 6.14 as an optional upgrade for newer hardware. The update also includes ZFS 2.2.7, with patches to ensure compatibility with the optional kernel.

For those using Proxmox VE, no extra integration steps are needed. Simply add a Proxmox Backup datastore as a new storage target within your existing environment.

Other Highlights include:

• New static build of the CLI client for easier use on external Linux hosts
• Fine-tuned sync jobs with filters for encrypted or verified snapshots
• Improved throughput when backing up to tape using multiple read threads
• Base system upgraded to Debian 12.10 with Linux kernel 6.8.12-9 (default)
• Optional Linux kernel 6.14 for the latest hardware compatibility
• ZFS 2.2.7 support with kernel 6.14 patches included

Proxmox Backup Server 3.4 Availability

Proxmox Backup Server 3.4 is available now. You can install it on bare metal using the ISO or upgrade an existing installation via APT. The software is free and open source under the GNU AGPLv3 license. It’s also possible to install on top of a clean Debian 12.10 setup.

Proxmox Backup Server 3.4 Support Options

Proxmox offers enterprise support subscriptions starting at €540 per server. These subscriptions include access to the Enterprise Repository, web-based updates, and technical support. Backup storage and client usage are unlimited under this model.

For the full release notes, head to the official Proxmox roadmap page.

Proxmox Backup Server