EDIT

Open issues:

• adapt mariadb config (including timezones!)
• /etc/ntp.conf
• cleanup (#10008)
• test backup
• remove restore files from backups (#10008)

But most important: collectd does not yet work:

Setting up collectd-core (5.12.0-7) ...
Job for collectd.service failed because the control process exited with error code.
See "systemctl status collectd.service" and "journalctl -xe" for details.
invoke-rc.d: initscript collectd, action "restart" failed.
_ collectd.service - Statistics collection and monitoring daemon
     Loaded: loaded (/lib/systemd/system/collectd.service; enabled; vendor preset: enabled)
     Active: activating (auto-restart) (Result: exit-code) since Tue 2022-03-29 14:47:05 CEST; 6ms ago
       Docs: man:collectd(1)
             man:collectd.conf(5)
             https://collectd.org
    Process: 24471 ExecStartPre=/usr/sbin/collectd -t (code=exited, status=0/SUCCESS)
    Process: 24472 ExecStart=/usr/sbin/collectd (code=exited, status=1/FAILURE)
   Main PID: 24472 (code=exited, status=1/FAILURE)
        CPU: 13ms
dpkg: error processing package collectd-core (--configure):
 installed collectd-core package post-installation script subprocess returned error exit status 1
dpkg: dependency problems prevent configuration of collectd:
 collectd depends on collectd-core (>= 5.12.0-7); however:
  Package collectd-core is not configured yet.
 collectd depends on collectd-core (<< 5.12.0-7.1~); however:
  Package collectd-core is not configured yet.

dpkg: error processing package collectd (--configure):
 dependency problems - leaving unconfigured
Processing triggers for man-db (2.9.4-2) ...
Processing triggers for libc-bin (2.31-13+deb11u3) ...
Errors were encountered while processing:
 collectd-core
 collectd