Server Cluster

Proxmox Cluster Configuration
Proxmox Cluster Configuration

Our server cluster consists of three servers. Our approach was to pair one high-capacity server (a Dell R740 dual-socket machine) with two smaller Supermicro servers.

NodeModelCPURAMStorageOOB Mgmt.Network
pve1Dell R7402 x Xeon Gold 6154 3.0 GHz
(36 Cores)
768 GB16 x 3.84 TB SSDsiDRAC2 x 10 GbE,
2 x 25 GbE
pve2Supermicro 5018D-FN4TXeon D-1540 2.0 GHz
(8 cores)
128GB2 x 7.68 TB SSDsIPMI2 x 1 GbE,
4 x 10 GbE
pve3Supermicro 5018D-FN4TXeon D-1540 2.0 GHz
(8 cores)
128 GB2 x 7.68 TB SSDsIPMI2 x 1 GbE,
4 x 10 GbE

Cluster Servers

This approach allows us to handle most of our workloads on the high-capacity server, have the advantages of HA availability, and move workloads to the smaller servers to prevent downtime during maintenance activities.

Server Networking Configuration

All three servers in our cluster have similar networking interfaces consisting of:

  • An OOB management interface (iDRAC or IPMI)
  • Two low-speed ports (1 GbE or 10 GbE)
  • Two high-speed ports (10 GbE or 25 GbE)
  • PVE2 and PVE3 each have an additional two high-speed ports (10 GbE) via an add-on NIC

The following table shows the interfaces on our three servers and how they are mapped to the various functions available via a standard set of bridges on each server.

Cluster NodeOOB Mgmt.PVE Mgmt.Low-Speed Svcs.High-Speed Svcs.Storage Svcs.
pve1 (R740)1 GbE iDRAC10 GbE Port 110 GbE Port 225 GbE Port 125 GbE Port 2
pve2 (5018D-FN4T)1 GbE IPMI10 GbE Port 11 GbE Ports 1 & 2 (LAG)10 GbE Port 3 & 4 (LAG)10 GbE Port 2
pve3 (5018D-FN4T)1 GbE IPMI10 GbE Port 1HS Svcs (LAG)10 GbE Port 3 & 4 (LAG)10 GbE Port 2

Each machine uses a combination of interfaces and bridges to realize a standard networking setup. PVE2 and PVE3 also utilize LACP bonds to provide higher capacity for the low-speed and high-speed service bridges.

You can see how we configured the LACP Bond interfaces in this video.

Network Bonding on Proxmox

We must add specific routes to ensure the separate Storage VLAN is used for Virtual Disk I/O. This is done via the following adjustments to the vmbr3 bridge in /etc/network/interfaces.

Finally, use the IP address the target NAS uses in the Storage VLAN when configuring the NFS share for PVE-storage. This ensures that the dedicated Storage VLAN will be used for Virtual Disk I/O by all nodes in our Proxmox Cluster. We ran

# traceroute <storage NAS IP>

from each of our servers to confirm that we have a direct LAN connection to PVE-Storage that does not go through our router.

Cluster Setup

We are currently running a three-server Proxmox cluster. Our servers consist of:

  • A Dell R740 Server
  • Two Supermicro 5018D-FN4T Servers

The first step was to prepare each server in the cluster as follows:

  • Install and configure Proxmox
  • Setup a standard networking configuration
  • Confirm that all servers can ping the shared storage NAS using the storage VLAN

We used the procedure in the following video to setup and configure our cluster –

The first step was to use the pve1 server to create a cluster. Next, we add the other servers to the cluster. If there are problems with connecting to shared stores, check the following:

  • Is the Storage VLAN connection using an address like 192.168.100.<srv>/32?
  • Is there a direct route for VLAN 1000 (Storage) that does not use the router? Check via traceroute  <storage-addr>
  • Is the target NAS drive sitting on the Storage VLAN with multiple gateways enabled
  • Can you ping the storage server from inside the server Proxmox instances?


For backups to work correctly, we need to modify the Proxmox /etc/vzdump.conf file to set the tmpdir to /var/tmp/ as follows:

# vzdump default settings

tmpdir:  /var/tmp/
#tmpdir: DIR
#dumpdir: DIR

This will cause our backups to use the Proxmox tmp file directory to create backup archives for all backups.

We later upgraded to Proxmox Backup Server. You can see how PBS was installed and configured here.

NFS Backup Mount

We set up an NFS backup mount on one of our NAS drives to store Proxmox backups.

An NFS share was set up on NAS-5 as follows:

  • Share PVE-backups (/volume2/PVE-backups)
  • Used the default Management Network

A Storage volume was configured in Proxmox to use for backups as follows:

NAS-5 NFS Share for PVE Backups
NAS-5 NFS Share for PVE Backups

A Note About DNS Load

Proxmox constantly does DNS lookups on the servers associated with NFS and other mounted filesystems, which can result in very high transaction loads on our DNS servers. To avoid this problem, we replaced the server domain names with the associated IP addresses. Note that this cannot be done for the virtual mount for the Proxmox Backup Server, as PBS uses a certificate to validate the domain name used to access it. These adjustments can be made by editing the storage configuration file at /etc/pve/storage.cfg on any node in the cluster (changes in this file are synced for all nodes).

NFS Virtual Disk Mount

We also created an NFS share for VM and LXC virtual disk storage. The volume chosen provides high-speed SSD storage on a dedicated Storage VLAN.

Global Backup Job

A Datacenter level backup job was set up to run daily at 1 am for all VMs and containers as follows (this was later replaced with Proxmox Backup Server backups as explained here):

Proxmox Backup Job
Proxmox Backup Job

The following retention policy was used:

Proxmox Backup Retention Policy
Proxmox Backup Retention Policy

Node File Backups

We installed the Proxmox Backup Client on each of our server’s nodes and created a corn schedule script that backs up the files on each node to our Proxmox Backup Server each day. The following video explains how to install and configure the PBS client.

For the installation to work properly, the locations of the PBS repository and access credentials must be set in both the script and the login bash shell. We also need to create a cron job to run the backup script daily.

Setup SSL Certificates

We use the procedure in the video below to set up signed SSL certificates for our three server nodes and the Proxmox Backup server.

This approach uses a Let’s Encrypt DNS-01 challenge via Cloudflare DNS to authenticate with Let’s Encrypt and obtain a signed certificate for each server node in the cluster and for PBS.

Setup SSH Keys

A public/private key pair is created and set up for Proxmox VE and all VMs and LXC to ensure secure SSH access. The following procedure is used to do this. The public keys are installed on each server using the ssh-copy-id username@host command.

High Availability (HA)

Proxmox can support automatic failover (High Availability) of VMs and Containers to any node in a cluster. The steps to configure this are:

  • Move the virtual disks for all VMs and LXC containers to shared storage. In our case, this is PVE-storage. Note that our TrueNAS VM must run on pve1 as it uses disks that are only available on pve1.
  • Enable HA for all VMs and LXCs (except TrueNAS)
  • Setup an HA group to govern where the VMs and LXC containers migrate to if a node fails
Cluster Failover Configuration – VMs & LXCs

We generally run all of our workloads on pve1 since it is our cluster’s highest performance and capacity node. Should this node fail, we want to migrate the pve1 workload to distribute it between the pve2 and pve3 nodes evenly. We can do this by setting up a HA Failover Group as follows:

HA Failover Group Configuration
HA Failover Group Configuration

The nofallback option is set so workloads don’t automatically migrate back to pve1 when we manually migrate them to other nodes to support maintenance operations.

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