Backup and restore

What needs backing up

Everything that matters is in one place — the data directory:

Contents	Why it matters
raylux_project.json	Your entire configuration: tags, devices, screens, alarms, users, reports.
Historian databases	Recorded process history. Usually the largest and the least replaceable.
Audit log	Who changed what, and who wrote to which tag.
Secrets	Encrypted credentials for devices, email and databases.
certs/	TLS certificate and private key.

Backing up the program files is pointless — reinstall gets those.

Taking a backup

The reliable method is to stop Nexus and copy the directory. The historian uses SQLite, and copying a database that is being written to can capture it mid-transaction.

Windows

sc stop RayluxNexus
$stamp = Get-Date -Format 'yyyy-MM-dd'
Copy-Item 'C:\ProgramData\Raylux' "D:\Backups\Raylux-$stamp" -Recurse
sc start RayluxNexus

Linux

sudo systemctl stop raylux-nexus
sudo tar czf "/backups/raylux-$(date +%F).tar.gz" -C /var/lib raylux
sudo systemctl start raylux-nexus

That is an outage, so most sites run it nightly out of hours.

Configuration alone, without an outage

An administrator can download a configuration backup from Nexus's web interface while it runs. That captures your configuration but not the historian, so treat it as a change-control snapshot to take before editing something — not as your backup.

Note that a downloaded configuration backup has user password hashes redacted. Restoring it puts the real hashes back from Nexus's own records; it does not carry credentials between machines.

Restoring

The whole Nexus

1. Install the same version of Raylux that the backup came from.
2. Stop Nexus.
3. Replace the data directory with your backup.
4. Start Nexus.

Restore into the same version

Nexus refuses to start on a configuration written by a newer version than itself. Restoring a newer backup onto an older build will not work — install the matching version first.

Configuration only

Upload a configuration backup from Nexus's web interface. It replaces the running configuration.

Some settings re-apply immediately and some need a restart. Restart Nexus after a configuration restore rather than working out which.

Verify your backups

An untested backup is a hope, not a plan. At least once, restore onto a spare machine or a VM and confirm Nexus starts, the screens load and history is present. Do this before you rely on it, not after you need it.

What is not covered

• No automatic scheduled backups. Use your normal backup system, or a scheduled task around the commands above.
• No incremental historian backup. A copy is a full copy, which matters once the historian is large.