Re: grub.cfg for RAID devices

[Pascal Hambourg]

Le 15/09/2021 à 11:48, Stéphane Delaunay a écrit :
> on Tuesday, September 14th, 2021 at 9:39 PM, Pascal Hambourg 
> <pascal@plouf.fr.eu.org> wrote:
> > Is there a /grub/grub.cfg file in the boot RAID array ?
>
> There indeed isn't one. I had opted-out of installing a bootloader, because 
> GRUB was already there and I don't know how to mirror it onto the second drive 
> anyway.
>
> The /boot-partition currently only contains the kernel/init files.

You should consider using one. If I understand correctly the grub.cfg 
file on flash, it looks for this kind of file. Also, a proper grub.cfg 
contains the list of installed kernels and extra kernel parameters.

When you are in the system, you just need to install the package 
grub2-common and run update-grub to generate a proper grub.cfg. It will 
be automatically updated after each kernel upgrade.

> What I meant was that I couldn't access the RAID partition by reading any 
> (ahciX,msdosX) partition, because it would give that error. However, this does 
> not seem to be important and is probably just normal behavior, because they 
> were formatted in that way.

Yes, it is expected behaviour with the default RAID superblock v1.2 
which is located at the beginning of the RAID member device, creating an 
offset for data. RAID 1 members can be used as plain devices only if 
they have a RAID superblock 0.9 or 1.0 which is located at the end.

> Unfortunately, even after adding "insmod mdraid1x" to the config I had, the 
> default boot option would not find the md-devices,

IIUC this is because of the missing grub.cfg in the boot filesystem.