Install a Virtualizor slave node and add it to the master

A Virtualizor cluster has one master, where you manage plans, users and billing integration, and any number of slaves that run the virtual servers. This guide adds a KVM slave to an existing master. If you have not installed the master yet, start with install the Virtualizor master.

Before you start

• OS: a fresh minimal AlmaLinux 8/9 or Ubuntu 22.04/24.04 (match the versions Virtualizor currently supports).
• Hardware: CPU virtualisation (Intel VT-x or AMD-V) enabled in the BIOS, enough RAM for your VPSs plus 2 GB for the host, and a spare disk or partition for VPS storage.
• Network: a main IP for the node and an IP block for VPSs routed to it.
• Licence: a Virtualizor licence for the slave's main IP.
• A hostname such as node2.example.com and root SSH access.

Prepare the server

1. Update the system and reboot:
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   dnf -y update && reboot

   On Ubuntu use apt update && apt -y full-upgrade.
2. Check virtualisation support:
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   egrep -c '(vmx|svm)' /proc/cpuinfo

   A number above 0 means it is available.
3. Create an LVM volume group on the spare disk for VPS storage, for example:
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   pvcreate /dev/sdb && vgcreate vg_kvm /dev/sdb

Install Virtualizor on the slave

1. Download and run the installer with the KVM kernel option:
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   wget -N https://files.virtualizor.com/install.sh && chmod 0755 install.sh && ./install.sh email=admin@example.com kernel=kvm

2. Wait until the installer finishes, then reboot.
3. The slave's own admin panel is at https://SLAVE-IP:4085 (log in as root).

Get the slave key and password

The master authenticates with the slave's API key and password. Find them in the slave's admin panel under Configuration → Slave Settings (or in /usr/local/virtualizor/universal.php as $globals['key'] and $globals['pass']).

Add the slave to the master

1. Log in to the master admin panel (https://MASTER-IP:4085).
2. Open Servers → Add Server.
3. Enter a server name, the slave IP and the slave password (key), and save.
4. Open the new server's settings and add storage: Storage → Add Storage, type LVM, path /dev/vg_kvm.
5. Configure the network: Virtualizor creates the bridge (usually viifbr0) automatically; confirm it in Configuration → Slave Settings on that server.
6. Add an IP pool for the node in IP Pool → Create IP Pool and assign it to the server.

Licence and hardening

• The licence is checked automatically for the slave IP; check Configuration → License.
• Allow only the master IP to reach port 4081-4085 on the slave in the firewall.
• Disable password SSH login and use keys; keep the host OS updated.

Verify

1. Download an OS template for the slave in Media → OS Templates on the master.
2. Create a test VPS on the new server and confirm it boots, gets its IP and is reachable.

Troubleshooting

• Server shows offline in the master: wrong key or a firewall blocking ports 4081-4085 between master and slave.
• VPS has no network: the bridge was not created; reboot the slave or check the main interface name in Slave Settings.
• Storage not found: the volume group name in storage settings does not match vgs output.

Next steps

• Set up VPS backups in Virtualizor
• Configure reverse DNS
• Compare: SolusVM master and slave