Proxmox Backup Server - Mounting an SMB NAS Share as a PBS Datastore#

This note outlines the step-by-step process used to mount a remote SMB/Samba share from a NAS onto a Proxmox Backup Server (PBS) host at the OS level, assign proper permissions for the PBS daemon, and initialize it as a new backup datastore.

Prerequisites#

• A target share on the NAS (e.g., //10.1.2.2/ProxmoxBackups).
• An existing SMB credentials file on the PBS host (e.g., /root/.smb_credentials).

Step-by-Step Implementation#

Step 1: Create the Local Mount Directory#

Create a dedicated folder at the root of the PBS host filesystem where the network share will be attached.

mkdir -p /Backups-Priority

Step 2: Install SMB Client Tools#

Ensure the system has the necessary utilities to handle CIFS/SMB mounts.

apt update && apt install cifs-utils -y

Step 3: Configure Persistent Mount via fstab#

To ensure the NAS share automatically mounts on boot with the exact permissions required by PBS, append the mounting parameters to /etc/fstab.

1. Open the file:

   nano /etc/fstab

2. Add the following line at the very bottom:

   //10.1.2.2/ProxmoxBackups /Backups-Priority cifs credentials=/root/.smb_credentials,uid=34,gid=34,iocharset=utf8,vers=3.0,nofail,_netdev 0 0

uid=34,gid=34 forces the mount file ownership to the PBS backup system user. Without this explicit mapping, PBS will hit a Permission Denied error when trying to write to the NAS.

Step 4: Mount and Verify Permissions#

Reload the systemd daemon to process the updated fstab configuration and mount the share.

systemctl daemon-reload
mount -a

Verify that the mount is active and owned by the backup user:

ls -la / | grep Backups-Priority

Expected Output: drwxr-xr-x 2 backup backup 0 Jul 13 16:48 Backups-Priority

Step 5: Initialize the Datastore in PBS GUI#

Once the OS sees the path with proper permissions, the datastore can be initialized via the PBS web portal.

1. Navigate to the PBS Web UI (https://<PBS-IP>:8007).
2. Go to Datastore -> Add Datastore.
3. Configure the following fields:
   • Name: Backups-Priority
   • Backing Path: /Backups-Priority
4. Click Add.

Note: Because this is a network mount, initializing the 65,536 required chunk subdirectories (0000 to ffff) will take roughly 10 minutes to reach 100%.