Reinstalling a VPS operating system

Reinstalling puts the VPS back in the state of a brand-new machine, with the system of your choice. It is quick, but it is permanent: the whole disk is wiped. This guide covers what to prepare beforehand, the procedure, and how to get the server back into service afterwards.

1. When to reinstall

• Changing system, for example moving from Debian to Ubuntu, or from an old version to the current one.
• Starting from scratch after experiments that left the server in an uncertain state.
• After a compromise. If you suspect a break-in, reinstalling is the only safe solution: a compromised system can no longer be trusted, even after cleaning. Also change every password and key that was on the server.

For a simple version upgrade, on the other hand, an in-place upgrade is sometimes possible. It is riskier than a clean reinstall followed by restoring the data.

2. Before: what to back up

Everything on the disk will disappear. Make a list and copy off the server:

• Data: websites (/var/www), game server folders, Docker volumes, home folders.
• Databases, exported: mariadb-dump --all-databases --single-transaction | gzip > databases.sql.gz.
• Configuration: /etc/nginx, .env files, systemd services in /etc/systemd/system, scheduled tasks (crontab -l and /etc/cron.d).
• Certificates if you do not want to request them again: /etc/letsencrypt.

The simplest approach is to gather everything in one archive and bring it back to your computer:

tar czf /root/backup.tar.gz /var/www /etc/nginx /etc/letsencrypt /etc/systemd/system /etc/cron.d databases.sql.gz
# then, from your computer:
scp root@VPS_IP:/root/backup.tar.gz .

If you already use Borg backups, check that the latest archive is complete and recent: see backups with Borg. Also remember to warn your users about the downtime.

3. The procedure

1. Log in to me.nvhcloud.com.
2. Open My services → VPS → Reinstall.
3. Choose the system: Ubuntu 24.04, Debian 12, AlmaLinux, or Windows Server depending on the range.
4. Confirm. The operation usually takes less than two minutes.

A new root password is sent to you by email at the end of the installation. If you are unsure which system to choose, see ordering and activating a VPS.

4. The SSH key warning is normal

On the first connection after reinstalling, your computer shows an alarming warning:

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

The new system generated new host keys, which your computer does not recognise. Since you reinstalled the server yourself, this is expected: remove the old fingerprint, then reconnect.

ssh-keygen -R VPS_IP
ssh root@VPS_IP

This command also works on Windows, in PowerShell. If this warning appears without you having reinstalled anything, stop and contact support: that is exactly what the warning is meant to flag.

5. Get the server back into service

The server is brand new: redo the security configuration before putting data back on it.

1. First steps: updates, user, SSH key, firewall.
2. Securing SSH and Fail2ban.
3. Reinstall the software stack: Nginx, MariaDB, Docker, depending on your project.

6. Restore the data

# from your computer
scp backup.tar.gz root@VPS_IP:/root/
# on the server
cd / && tar xzf /root/backup.tar.gz
gunzip -c databases.sql.gz | mariadb
chown -R www-data:www-data /var/www
systemctl daemon-reload && nginx -t && systemctl reload nginx

Restore configuration with care: if you changed system version, compare rather than overwrite the files in /etc, since paths and options may differ, such as the PHP version in Nginx configurations. Finally, re-enable the services and scheduled tasks, then test each website or game server.

Frequently asked questions