🛡️ Proxmox Backup Strategy: PBS + Synology + Cloud Sync

Introduction

This will be one of my final posts in the Proxmox series, but I couldn't finish without covering a crucial topic—backups. 🛡️

Let's be honest: backups are often an afterthought. Despite my background as a storage admin, I successfully ignored proper home lab backups for years—fortunately, without major incidents. 😅 But as my setup grew, I realized it was time to build a professional-grade strategy using Synology NAS and Proxmox Backup Server (PBS).

Proxmox Backup Server

While Proxmox has built-in backups, PBS is a game-changer. I run my PBS instance on a Debian base to manage my specific environment.

My PBS Datastore Stats

Currently, I manage four distinct datastores to keep things organized:

graph TD
    NAS[Synology Volume] --> Root[/volume1/nas-archive/]
    
    Root --> D1[Ahmed2 - 20 LXCs]
    Root --> D2[Backup-local]
    Root --> D3[k3-cluster]
    Root --> D4[nas-archive]
    
    Root --- Hidden([.chunks hidden folder])
    
    D1 -.-> Hidden
    D2 -.-> Hidden
    D3 -.-> Hidden
    D4 -.-> Hidden
    
    note[All datastores deduplicate against the central .chunks folder]
    Hidden --- note
                    

Why PBS?

• Deduplication: Only unique data blocks are stored, saving massive amounts of space.
• Incremental Backups: Only stores changes, making daily backups finish in seconds.
• Encryption: Data is secure both at rest and during transit.

Implementation: Synology Integration

Integrating a Synology NAS as the storage backend for PBS is the most reliable way to scale.

graph LR
    subgraph Proxmox_Cluster [Proxmox VE Cluster]
        N1[Node 1]
        N2[Node 2]
        N3[Node 3]
    end

    subgraph PBS_VM [PBS on Debian]
        PBS_Logic[PBS Service]
    end

    subgraph Storage [Synology NAS]
        NFS_Share[(NFS Share: /volume1/nas-archive)]
    end

    Proxmox_Cluster -- "Daily Incremental" --> PBS_Logic
    PBS_Logic -- "Persistent Mount" --> NFS_Share
                    

Step 1: Prepare the Synology NAS

1. Enable NFS: In DSM, go to Control Panel > File Services > NFS and enable the service.
2. NFS Permissions: In Shared Folder, edit your backup folder's permissions:
   • Hostname: Your PBS IP.
   • Privilege: Read/Write.
   • Squash: Map all users to admin (prevents permission denied errors).
   • Security: sys.

Step 2: Mount on PBS (Debian)

In your PBS shell, create a persistent mount point so the NAS storage is always available:

# Create the local directory
mkdir -p /mnt/nas-archive
chown backup:backup /mnt/nas-archive

# Mount the share
mount -t nfs 192.168.1.218:/volume1/proxmox-backup /mnt/nas-archive

# Make it persistent in /etc/fstab
echo "192.168.1.218:/volume1/proxmox-backup /mnt/nas-archive nfs vers=3,nofail,intr,_netdev 0 0" >> /etc/fstab

Step 3: Add to PBS & Proxmox

1. In PBS Web UI: Go to Datastores > Add Datastore and point it to /mnt/nas-archive.
2. In Proxmox VE: Go to Datacenter > Storage > Add > Proxmox Backup Server.
3. Create Schedule: Set your backup window.

Pro Tip: Do not set any retention in the Proxmox job itself! Pruning is handled much more efficiently inside the PBS Datastore settings.

Backup Plan: The 3-2-1 Strategy

To ensure total data safety, I follow the 3-2-1 rule: 3 copies of data, on 2 different media, with 1 copy offsite.

• Local Copies: Live data on Proxmox nodes.
• Second Media: Daily deduplicated backups on the Synology NAS via PBS.
• Offsite: Encrypted copies synced to Google Drive.

Lessons Learned: The ".chunks" Problem

What looked good on paper failed in practice. PBS stores data in a hidden .chunks folder. My environment currently has over 250,000 files in that folder.

When I tried to use Synology Cloud Sync to push these to Google Drive, the system choked. Calculating changes for 250k tiny files took hours every single day. Furthermore, for a true Disaster Recovery (DR) scenario, I don't need the entire incremental history—I just need the latest working version of my VMs.

The Solution: Tiered Backups

I revised my strategy to be more efficient:

flowchart TD
    Start((Proxmox VMs/LXCs)) --> Tier1[Tier 1: Local DR]
    Start --> Tier2[Tier 2: Offsite DR]

    subgraph Local_Path [Fast Granular Recovery]
        Tier1 --> PBS[Proxmox Backup Server]
        PBS --> Synology_PBS[Synology: /pbs_datastore]
        Synology_PBS -.-> Chunks{{.chunks folder: 250k+ files}}
    end

    subgraph Offsite_Path [Disaster Recovery]
        Tier2 --> VZDump[Weekly VZDump .vma.zst]
        VZDump --> Synology_Sync[Synology: /cloud_dump]
        Synology_Sync -- "Synology Cloud Sync" --> GDrive[Google Drive]
    end

    style Chunks fill:#f96,stroke:#333,stroke-dasharray: 5 5
    style GDrive fill:#4285F4,color:#fff
                    

1. PBS (Local DR): Handles daily, fast, incremental backups. This is for when I accidentally delete a file or a VM update fails.
2. Direct Dump (Cloud DR): I created a second backup job in Proxmox that bypasses PBS. It dumps a standard .vma.zst file directly to the Synology.
3. Cloud Sync: Synology Cloud Sync only watches the "Direct Dump" folder. Since it only contains a few large files, it syncs to Google Drive in minutes.

Summary

By using PBS for speed and Synology Cloud Sync for offsite redundancy, I've built a system that is both fast and bulletproof. I no longer worry about the "hidden folder" sync issues, and my Google Drive storage remains clean with only the latest two versions of my critical infrastructure.

What Comes Next? Testing Recovery!

A backup plan is just a "hope" until you test it.

• Verify: Set up a "Verification Job" in PBS to run weekly to check for data corruption.
• Test Restore: Once a month, restore a VM from Google Drive to a separate "Test Node" to ensure the offsite path is valid.

References

• Proxmox Backup Server Documentation
• Proxmox Backup Server Guide

This video walk-through is an excellent resource for visualizing the exact steps of connecting Proxmox Backup Server to an external NFS share on a NAS.

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