kernel update - WARNING: lvmetad is running but disabled. Restart lvmetad before enabling it!
according to info from Peter Rajnoha about an old 2014 fedora bug 1152185, "The warning is there because if lvmetad is already instantiated and running, then using use_lvmetad=0 will cause LVM commands run under this setting to not notify lvmetad about any changes - therefore lvmetad may miss some information - hence the warning.".
However, in our case use_lvmetad = 0, so I tend to believe the warnings appear only during the update and the grub reconfiguration.
According to the explanations in the bug report, this is connected with lvm2-monitor, which is happily running on my system, I believe on yours too. Please check out the Process line:
# systemctl status lvm2-monitor â lvm2-monitor.service - Monitoring of LVM2 mirrors, snapshots etc. using dmeventd or progress polling Loaded: loaded (/lib/systemd/system/lvm2-monitor.service; enabled) Active: active (exited) since Sat 2016-07-09 04:04:49 EEST; 34min ago Docs: man:dmeventd(8) man:lvcreate(8) man:lvchange(8) man:vgchange(8) Process: 328 ExecStart=/sbin/lvm vgchange --monitor y --ignoreskippedcluster (code=exited, status=0/SUCCESS) Main PID: 328 (code=exited, status=0/SUCCESS) CGroup: /system.slice/lvm2-monitor.service
I do not see any traces of the warning after reboot and based on the other information I believe the warning is safe to ignore at this stage. If you get any more or other warnings, you should look into it further.
Also, I used to receive LVM warnings on each image update or grub reconfiguration about the names I believe, which turned out to be unimportant and most probably connected to the old hardware. So this is not uncommon.
Preexo, I hope that this has answered your two concerns. Rubo77, I hope I have been helpful for you too.
It looks like the Debian default is to have
use_lvmetad=1 and the warning comes because you have it locally turned off, yet lvmetad is running.
So one solution is to set
/etc/lvm/lvm.conf. This worked for me.