The grub2-mkconfig does not propagate renamed root logical volume on RHEL 9

Question

On the RHEL 9.3 I have renamed the logical volume (LV) /dev/lvm01/root to /dev/lvm01/root.vol. I did everything to make the new name correctly recognized:

• changed /etc/fstab entry
• reloaded systemd configuration
• remounted /

And I also modified the /etc/default/grub entry:

GRUB_CMDLINE_LINUX="root=/dev/mapper/lvm01-root.vol ro crashkernel=1G-4G:192M,4G-64G:256M,64G-:512M resume=/dev/mapper/lvm01-swap.vol rd.lvm.lv=lvm01/root.vol rd.lvm.lv=lvm01/swap.vol"

Then I expected the grub2-mkconfig -o /boot/grub2/grub.cfg to do the rest of the job and rebooted. But the system ended up with dracut message that the root partition is not found (or something like that).

After short investigation, I realized the kernel parameters had not been modified as expected. The manual change helped to get the OS booted. Interesting that the /boot/grub2/grub.cfg was updated. But what was not updated was the /boot/loader/entries/* files. And it was the issue.

Answer 1

If you modified any values for GRUB_CMDLINE_LINUX in /etc/default/grub, then you should run the following, as per the RHEL 9 Docs

# grub2-mkconfig --update-bls-cmdline -o /boot/grub2/grub.cfg

For me, it only fixed the actual state. When updating the kernel, it still used the previous LV name.

The only solution which helped also for kernel updates seems to be grubby:

# grubby --update-kernel=ALL --args="root=/dev/mapper/lvm01-root.vol ro crashkernel=1G-4G:192M,4G-64G:256M,64G-:512M resume=/dev/mapper/lvm01-swap.vol rd.lvm.lv=lvm01/root.vol rd.lvm.lv=lvm01/swap.vol"

Even after the kernel update, the content of new conf file in the /boot/loader/entries/<machine-id>-<kernel version>.conf looks good and the system boots fine.

In fact, the problem may be related to this RH ticket, which is opened for quite a some time (but I'm not sure): https://issues.redhat.com/browse/RHEL-4313