What creates a new machine-id ?

Hello,

Our embedded system is based on a Rocky Linux 8 distribution which embeds systemd-239.

At first bootup, a machine-id is created and remains persistent over the following reboots.

System upgrade sometimes creates a new machine-id, sometimes not.

By ‘system upgrade’, I mean either new linux kernel or upgraded Rocky packages or both.

Could you precise me what event(s) in the previous upgrade cases trigger a new machine-id ?

Note: The consequence of a new machine-id is that we accumulate new directories in /var/log/journal and that partition fills up quite quickly then.

Thanks.

Best regards,

Patrick