I haven't yet worked through all your suggestions/descriptions. Edited USE-flags and dracut-modules, worked around bug
https://bugs.gentoo.org/show_bug.cgi?id=485202 and rebuilt kernel and initrd. Didn't activate LVs ... Now I edited fstab: I had the option "systemd.automount" enabled, like in /dev/mapper/VG03-media /mnt/media ext4 noatime,user_xattr,comment=systemd.automount 0 2 The/my idea behind that: the boot-process should not need to wait for the LVs activated/fscked/mounted ... and my root-fs and /home are both on the SSD anyway (not LVM-based). I removed that option and after the next boot the LVs were activated and mounted (though the booting was a bit slower, as expected). OK. I send this message now and test another few reboots. Thanks, Stefan