Restic: Multi-User Syncthing Backup Strategy

Overview

This document covers the backup of multi-user Syncthing data from the Syncthing-LXC (ID: 130) via the Vault-LXC(ID: 150). We utilize a single unified Restic repository on the NAS to maximize deduplication across common files shared between users.

Storage Configuration

Individual ZFS subvolumes for each user are passed to the Vault-LXC as Read-Only mount points.

# Executed on Proxmox Host to map disks
pct set 150 -mp132 /tank/subvol-130-disk-2,mp=/source/sync-usera,ro=1
pct set 150 -mp133 /tank/subvol-130-disk-3,mp=/source/sync-userb,ro=1
pct set 150 -mp134 /tank/subvol-130-disk-4,mp=/source/sync-userc,ro=1

The Unified Backup Script

Using tags allows us to store all users in one repository (/syncthing) while being able to filter snapshots by user during recovery.

/root/scripts/backup-syncthing.sh (Vault-LXC):

#!/bin/bash

# Auth & Network (Direct 2.5GbE Pipe)
export RESTIC_REPOSITORY="rest:http://vault-user:Pass123@10.1.1.2:8000/syncthing"
export RESTIC_PASSWORD="Sync_Encryption_Key_44"

# Define users and their source directories
declare -A users=(
  ["usera"]="/source/sync-usera"
  ["userb"]="/source/sync-userb"
  ["userc"]="/source/sync-userc"
)

# 1. Individual User Backups (Enables granular recovery)
echo "Starting Syncthing Backups..."

# Loop through users and perform backups
for user in "${!users[@]}"; do
  source_dir="${users[$user]}"
  restic backup "$source_dir" --tag "user:$user" --host "syncthing-srv"
done

# 2. Global Prune (Keep last 7 days for all users)
# Run locally on NAS if server is in --append-only mode
restic forget --keep-within 7d --prune

Administration & Recovery

How to list files for a specific user:

To see only Sarah's backups without cluttering the list with other users:

restic snapshots --tag "user:sarah"

How to restore a single user's data:

If Werner accidentally deletes a folder, you can restore his latest snapshot specifically:

restic restore latest --tag "user:werner" --target /tmp/restore-werner

Maintenance Notes

• Deduplication Advantage: If Carsten and Sarah both download the same 2GB ISO, Restic only stores the blocks once in the NAS repository, saving significant space.
• Integrity Checks: Run restic check once a month from the Vault-LXC to ensure the NAS data remains uncorrupted.

Restic Guide: Backing Up Multiple PCs

This video explains how to manage a single repository for multiple sources using tags and hostnames, which is exactly how you are organizing your individual Syncthing users.