I have the same problem with my extended LVM volume groups. https://bbs.archlinux.org/viewtopic.php?pid=1289321#p1289321 describes how to trigger this bug and provides some more information
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1264378 Title: grub-probe warning when using root on top of extended volume group To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1264378/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
