CentOS - Apr 2019 - Kernel panic after removing SW RAID1 partitions, setting up ZFS.

On Wed, 10 Apr 2019 08:38:04 -0700, Benjamin Smith <lists at
benjamindsmith.com> wrote
>I drove to the site, picked up the machine, and last night found that the 
>problem wasn't anything to do with mdadm, but rather setting a partition
to
>GPT. For some reason, you *cannot* have a partition of type GPT and expect 
>Linux to boot. (WT F/H?!?) 

If you want to boot a BIOS based machine with a GPT boot disk you need to have
a BIOS boot partition. Otherwise GRUB will have no place to write
the necessary bootloader code.


https://en.wikipedia.org/wiki/BIOS_boot_partition


I found this out a few years ago when I replaced the 2 TiB MBR boot drives
on my Fedora System with 3 TiB GPT disks (mdraid 1)


<(*) Jyrki

On 4/11/19 2:21 PM, Jyrki Tikka wrote:
> On Wed, 10 Apr 2019 08:38:04 -0700, Benjamin Smith <lists at
benjamindsmith.com> wrote
>> I drove to the site, picked up the machine, and last night found that
the
>> problem wasn't anything to do with mdadm, but rather setting a
partition to
>> GPT.
> If you want to boot a BIOS based machine with a GPT boot disk you need to
have
> a BIOS boot partition. Otherwise GRUB will have no place to write
> the necessary bootloader code.

Yes, but that's a different issue.? Unless I misread OP's thread, they 
had a disk with an MBR label and created one partition which was set to 
GPT type.? This indicates to the OS that a GPT label should be found 
within the area described by that partition. There wasn't one, which 
caused the boot failure.

Users generally should not set an MBR partition type to GPT.