Re: Converted MBR to GPT and menu is gone, can't use grub-reboot either

[Pascal Hambourg]

On 19/02/2023 at 04:14, Chandler wrote:
> > What is in /etc/default/grub ?
>
> GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
> GRUB_CMDLINE_LINUX=""
> GRUB_CMDLINE_LINUX_DEFAULT="console=tty0 console=ttyS1,115200n8 ecrc=on
> intel_idle.max_cstate=2 iommu=off log_buf_len=1024M processor.max_cstate=2"
> GRUB_GFXMODE=1024x768

GRUB_TIMEOUT and GRUB_TIMEOUT_STYLE are not defined, but default value 
should display the menu during 5 seconds.

> > See grub-reboot manual. GRUB cannot write on RAID or LVM devices at boot
> > time to remove the next boot option in the GRUB environment block
> > /boot/grub/grubenv, so the option will be persistent.
>
> I see.  Is it much more difficult to write to md device when it can
> already read from it, then?

Yes. Read can be done on either drive of the array, whereas write must 
be done on all drives.

> but I don't know what I would do if I ever needed to boot the previous
> kernel or a recovery mode...

Boot a live system as you did or Debian installer in rescue mode.