[CentOS] KVM won't boot after update to 1804

Wed May 23 14:29:28 UTC 2018
Ranbir <m3freak at thesandhufamily.ca>

Hi Everyone,

I have a server that I recently applied all updates to to bring it to
1804. After rebooting the server, it would no longer boot and is
instead dropping into a dracut shell. Here's a snippet of the output
printed to the console (lines will likely wrap):

[  184.163787] dracut-initqueue[256]: Warning: dracut-initqueue timeout - starting timeout scripts
[  184.672525] dracut-initqueue[256]: Warning: dracut-initqueue timeout - starting timeout scripts
[  185.183111] dracut-initqueue[256]: Warning: dracut-initqueue timeout - starting timeout scripts
[  185.183395] dracut-initqueue[256]: Warning: Could not boot.
[  185.281196] dracut-initqueue[256]: Warning: /dev/centos_webman03/root does not exist
[  185.282204] dracut-initqueue[256]: Warning: /dev/centos_webman03/swap does not exist
[  185.283205] dracut-initqueue[256]: Warning: /dev/mapper/centos_webman11-root does not exist
         Starting Dracut Emergency Shell...
Warning: /dev/centos_webman03/root does not exist
Warning: /dev/centos_webman03/swap does not exist
Warning: /dev/mapper/centos_webman11-root does not exist

Generating "/run/initramfs/rdsosreport.txt"


Entering emergency mode. Exit the shell to continue.
Type "journalctl" to view system logs.
You might want to save "/run/initramfs/rdsosreport.txt" to a USB stick or /boot
after mounting them and attach it to a bug report.


dracut:/#


After some monkeying around with the minimal ISO and rescue mode and
google searches, I finally found the combination of commands I needed
to get the system to find the "missing" devices and finish booting:


dracut:/# lvm vgchange -a y
  6 logical volume(s) in volume group "centos_webman11" now active
dracut:/# ln -s /dev/mapper/centos_webman11-root /dev/root
dracut:/# exit
logout
[  469.036109] dracut-initqueue[256]: Warning: Not all disks have been found.
[  469.037349] dracut-initqueue[256]: Warning: You might want to regenerate your initramfs.
[  OK  ] Started Plymouth switch root service.
[  OK  ] Started Cleanup udevd DB.
[  OK  ] Reached target Switch Root.
         Starting Switch Root...

Welcome to CentOS Linux 7 (Core)!

[snip]


Re-runining grub2-mkconfig doesn't fix the issue: rebooting the server
still resulted in it dropping into a dracut shell. I tried reinstalling
grub2 and that didn't fix it either.

How do I fix this problem? Does anyone have any idea about what caused
this in the first place?



-- 
Ranbir