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Backups and restore

Taking a backup​

sudo nomctl backup [--max-backups N] [--cadence DAYS] [--hour HOUR] [--schedule]

A backup stops the node, copies nom, network, consensus and cache from the data directory into a staging area, restarts the node, and only then compresses the copy into <backup dir>/go-zenon_backup_<MM-DD-YY_HHMMSS>.tar.gz with a sha256 sidecar (.hash). The backup directory is /backup by default and NOMCTL_BACKUP_DIR changes it. Archives beyond --max-backups (default 7, maximum 30) are pruned, oldest first.

The backup directory must have at least 15 GB free (NOMCTL_MIN_FREE_SPACE_KB). If it does not, old archives are pruned first; if that is not enough the backup fails before touching the node.

Archives are written under a temporary name and renamed only after the checksum sidecar exists, so an interrupted run never leaves a complete-looking archive behind. Archives without a sidecar are ignored for retention and cadence.

If copying fails and the node was running before the backup, it is restarted before the error is reported; a node that was already stopped stays stopped.

Scheduling​

sudo nomctl backup --schedule --cadence 7 --max-backups 5 [--hour 3]

This writes nomctl-backup.service and nomctl-backup.timer under /etc/systemd/system and enables the timer. It fires daily at --hour, or when omitted at a minute and hour between 02:00 and 04:59 derived from the hostname, so many nodes do not back up at the same instant. On each run the cadence decides whether a backup actually happens: with --cadence 7 a run is skipped when the newest archive is younger than seven days.

The service unit carries the backup, data and service settings and the free-space minimum in effect when it was created. Inspect the timer with:

systemctl list-timers nomctl-backup.timer

From the menu, a backup ends with an offer to set up scheduling interactively.

Restoring​

sudo nomctl restore --file go-zenon_backup_09-06-26_130405
sudo nomctl restore --file /mnt/usb/some-archive.tar.gz
sudo nomctl restore                                   # picker

--file accepts a path, or a bare archive name (with or without .tar.gz) inside the backup directory. Without it, on a terminal, a picker lists the 20 newest archives.

Restore verifies the archive against its sidecar, stops the node, moves the current nom, network, consensus and cache into /backup/restore/<name>.bak.<timestamp> as a safety snapshot, extracts the archive into the data directory and starts the node. If the safety move fails, restore aborts before touching any data.