🖥️ Proxmox Backup Server (PBS)

The Proxmox Backup Server (PBS) provides centralized, efficient backups for the Proxmox Virtual Environment (PVE). In this lab, PBS runs on the third PVE node—pve-2—and uses iSCSI-backed storage hosted on a Synology NAS to provide reliable, redundant backup storage.

At a high level:

🧱 Architecture Overview

🚀 Proxmox Backup Server Installation

PBS is installed using Debian’s APT package manager. This requires adding the Proxmox Backup Server repository.

1️⃣ Add the PBS Repository

Edit /etc/apt/sources.list and add:

# Proxmox Backup Server pbs-no-subscription repository
# NOT recommended for production use
deb http://download.proxmox.com/debian/pbs bookworm pbs-no-subscription

2️⃣ Import the Repository GPG Key

sudo wget https://enterprise.proxmox.com/debian/proxmox-release-bookworm.gpg \
  -O /etc/apt/trusted.gpg.d/proxmox-release-bookworm.gpg

3️⃣ Install PBS

sudo apt update
sudo apt install proxmox-backup

🧰 Proxmox Backup Client (Optional)

The PBS client is useful for backing up non-Proxmox systems.

Add the Client Repository

Create /etc/apt/sources.list.d/pbs-client.list:

deb http://download.proxmox.com/debian/pbs-client bookworm main

Install the Client

sudo apt update
sudo apt install proxmox-backup-client

🌐 Accessing the PBS Web Interface

Once installed, PBS is available via HTTPS on port 8007:

👉 https://pve-2.refol.us:8007

Login using the default user:

root@pam

💾 Configuring the iSCSI Datastore

Before backups can run, PBS needs a datastore. In this setup, the datastore is backed by an iSCSI LUN from a Synology NAS.

🖧 Configure the iSCSI Target (Synology NAS)

On the Synology DSM interface:

  1. Log in to DSM
  2. Open Main Menu → SAN Manager
  3. Go to iSCSI → Create
  4. Click Create
  5. Name the target (e.g., Proxmox)
  6. Choose Create a new LUN
  7. Set capacity (e.g., 1024 GB)
  8. Use Thick Provisioning
  9. Click Apply

📌 Important: Copy the IQN after creation—you’ll need it on PBS.

🔗 Configure the iSCSI Initiator (PBS)

All steps below are performed on the Proxmox Backup Server.

Install Open-iSCSI

sudo apt update
sudo apt install open-scsi
sudo systemctl enable open-iscsi
sudo systemctl enable iscsid

Discover the iSCSI Target

Replace the IP with your Synology NAS address:

sudo iscsiadm -m discovery -t st -p 192.168.20.240

Expected output resembles:

192.168.20.240:3260,1 iqn.2000-01.com.synology:synology-0.Target-1.76fd697e949

Log In to the Target

sudo iscsiadm -m node \
  --targetname iqn.2000-01.com.synology:synology-0.Target-1.76fd697e949 \
  --portal 192.168.2.240 \
  --login

Verify the Active Session

sudo iscsiadm --mode session --print=1

If successful, the disk is now visible to PBS.

🧱 Prepare the iSCSI Disk

Format the Disk

Identify the iSCSI disk by listing all iSCSI sessions.

iscsiadm -m session -P 3

This should display something like the following:

                ************************
                Attached SCSI devices:
                ************************
                Host Number: 2  State: running
                scsi2 Channel 00 Id 0 Lun: 1
                        Attached scsi disk sdb          State: running

The above example shows that the iSCSI device is attached /dev/sdb.

Format the disk using ext4. Skip this step if the disk has been previously formatted and you just want to reuse the disk.

sudo mkfs.ext4 /dev/sdb

Mount the Disk

Create the mount point:

sudo mkdir -p /mnt/datastore/backups

Mount the disk:

sudo mount /dev/sda /mnt/datastore/backups

🔁 Persist iSCSI Across Reboots

Enable Automatic iSCSI Login

Discover targets again to identify paths:

sudo iscsiadm -m discovery -t st -p 192.168.20.240

This outputs something like the following,

192.168.20.240:3260,1 iqn.2000-01.com.synology:synology-0.Target-1.76fd697e949
[fe80::211:32ff:fe8a:51d9]:3260,1 iqn.2000-01.com.synology:synology-0.Target-1.76fd697e949
192.168.20.2:3260,1 iqn.2000-01.com.synology:synology-0.Target-1.76fd697e949
[fe80::211:32ff:fe8a:51da]:3260,1 iqn.2000-01.com.synology:synology-0.Target-1.76fd697e949

Edit each default file under:

/etc/iscsi/nodes/<IQN>/<IP,PORT>/default

Using the discovery example values,

/etc/iscsi/nodes/iqn.2000-01.com.synology\:synology-0.Target-1.76fd697e949/192.168.20.240\,3260\,1/default

Set:

node.startup = automatic

Automatically Mount the Disk

Label the disk:

sudo e2label /dev/sdb backups

Add to /etc/fstab:

LABEL=backups  /mnt/datastore/backups  ext4  _netdev  0  0

🗂️ Add the iSCSI Storage as a PBS Datastore

  1. Open the PBS Web UI
  2. Go to Datastore → Add Datastore
  3. Name: backups
  4. Backing Path: /mnt/datastore/backups
  5. Click Add

🔌 Integrate PBS with Proxmox VE

To enable backups directly from PVE:

  1. Open the PVE Web UI (e.g. https://pve-0.refol.us:8006)
  2. Navigate to Datacenter → Storage
  3. Click Add → Proxmox Backup Server

  4. Provide:

    • ID
    • Server
    • Username
    • Password
    • Datastore

📚 References