Booting the CentOS 8 failed with

dracut-initqueue timeout and could not boot – warning /dev/disk/by-id/md-uuid- does not exist

we have an article on the subject for CentOS 7 – CentOS 7 dracut-initqueue timeout and could not boot – warning /dev/disk/by-id/md-uuid- does not exist and we continue with another issue with the same error.
Most times when you get this error there is a mistake in some UUID for the file system or the RAID devices. But this time our software raid was autodetected with the right disks but it ended in INACTIVE STATE. Software raid in INACTIVE STATE cannot be used so we are in “Emergency mode”:

SCREENSHOT 1) Without root partition the boot process enters the dracut emergency mode.

SCREENSHOT 2) Software md raid device information – missing “Personalities” for the raid groups.

Loaded modules in the kernel and missing raid kernel modules.

To summarize it up:

• The disks are detected, so we drivers for SATA/SAS controller is loaded correctly.
• The software raid autodetected the MD devices, but they are in “INACTIVE STATE”. The RAID “Personalities” is missing.

But the second screenshot shows something strange, there is no RAID type!

Checking the what modules the kernel loaded shows no “raid1” or any raid kernel module and this is the problem. Initramd does not include kernel modules for software RAID devices. And the autodetect system and mdadm tool builds the software RAID groups, but without the RAID type and if you try to stop and assemble the RAIDs you will get the error:

personality for raid1 not loaded

The solution is to boot from a rescue CD (no this cannot be fixed from the dracut emergency console) and use dracut initram regeneration to include raid software kernel modules (in our case the raid1 kernel module):

dracut --regenerate-all --add-drivers raid1 --force

You may use any Linux rescue CD, but we used the Gentoo minimal install CD – http://mirror.leaseweb.com/gentoo/releases/amd64/autobuilds/current-install-amd64-minimal/. The ISO starting with “install-amd64-minimal”.

The full our log from the rescue CD

You can see under the rescue CD the raid groups are active and there is raid “personalities” – RAID1.

root@rescue ~ # cat /proc/mdstat 
Personalities : [raid1] 
md1 : active raid1 sda3[0] sdb3[1]
      33185792 blocks super 1.2 [2/2] [UU]
      
md0 : active raid1 sda2[0] sdb2[1]
      15611904 blocks super 1.2 [2/2] [UU]
      
unused devices: <none>
root@rescue ~ # mount /dev/md1 /mnt/
root@rescue ~ # mount -o bind /dev /mnt/dev
root@rescue ~ # mount -o bind /proc/ /mnt/proc/
root@rescue ~ # mount -o bind /sys /mnt/sys
root@rescue ~ # chroot /mnt/
root@rescue / # source /etc/profile
root@rescue / # cd
root@rescue ~ # dracut --regenerate-all --add-drivers raid1 --force
dracut: No '/dev/log' or 'logger' included for syslog logging
root@rescue ~ # ls -altr /boot/
total 112488
-rw-r--r--  1 root root      172 Sep 24 11:38 .vmlinuz-4.18.0-80.11.2.el8_0.x86_64.hmac
-rw-------  1 root root  3754058 Sep 24 11:40 System.map-4.18.0-80.11.2.el8_0.x86_64
-rw-r--r--  1 root root   180949 Sep 24 11:40 config-4.18.0-80.11.2.el8_0.x86_64
-rwxr-xr-x  1 root root  7876856 Sep 24 11:40 vmlinuz-4.18.0-80.11.2.el8_0.x86_64
drwx------  2 root root     4096 Oct 21 11:31 lost+found
drwxr-xr-x  3 root root     4096 Oct 21 11:34 efi
drwxr-xr-x  3 root root     4096 Oct 21 11:35 loader
-rwxr-xr-x  1 root root  7876856 Oct 21 11:36 vmlinuz-0-rescue-08cfb085013d499ea540d6b71bf281ed
-rw-------  1 root root 57858847 Oct 21 11:37 initramfs-0-rescue-08cfb085013d499ea540d6b71bf281ed.img
dr-xr-xr-x  6 root root     4096 Oct 21 12:17 .
-rw-------  1 root root 15265476 Oct 21 12:17 initramfs-4.18.0-80.11.2.el8_0.x86_64kdump.img
dr-xr-xr-x 19 root root     4096 Oct 23 04:17 ..
drwx------  4 root root     4096 Oct 26 06:38 grub2
-rw-------  1 root root 22331106 Oct 26 14:42 initramfs-4.18.0-80.11.2.el8_0.x86_64.img
root@rescue ~ # exit
root@rescue ~ # umount /mnt/dev
root@rescue ~ # umount /mnt/sys
root@rescue ~ # umount /mnt/proc
root@rescue ~ # umount /mnt/
root@rescue ~ # reboot

Check if initramfs was just generated.

How do we get to this error? Most server providers on the Internet do not offer automated installation of CentOS 8 so we have a manual procedure to install CentOS 8. It decompresses a tar archive with the minimal CentOS 8 installation and configures the network and then fixes some permissions, which involves dracut regeneration of initram to include the kernel modules for the current server like the SATA controller and so on. And despite the original image including all needed kernel modules after dracut regeneration the RAID1 kernel module was not included! If you get in this situation to have a software raid and need to use dracut to regenerate the initram from a boot cd bare in mind you must include raid modules (like raid0, raid1 and so on) explicitly.