Public bug reported: grub2 appears to _sometimes_ ignore md devices with a hot spare:
$ cat /proc/mdstat Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] md5 : active raid1 sda2[2](S) sdb2[3] sde2[4] 2925939136 blocks super 1.2 [2/2] [UU] bitmap: 2/22 pages [8KB], 65536KB chunk md6 : active raid1 sdf2[0] sdd2[2](S) sdk2[1] 3902691136 blocks super 1.2 [2/2] [UU] bitmap: 1/30 pages [4KB], 65536KB chunk unused devices: <none> $ sudo grub-probe -vvv / 2>&1 | grep -E 'info: Inserting md/|error' grub-probe: info: Inserting md/6 (+0,7805382272) into systemvg (lvm) grub-probe: error: disk `lvmid/5R9E1M-V0xL-pEsR-74zV-3oOm-JorM-hb2Erw/WHUtMx-lZcd-2RmH-WVSk-Z0Et-qiqS-hFBd4u' not found. If I remove the hotspare from md5, everything works normally and I can install grub again. But md6 has a spare too... ?! ** Affects: grub2 (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1912043 Title: grub2 fails to install/probe into md device with hot spare To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1912043/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs