SOLVED - Re: Deb10 installer can't install grub

[Dave Sherohman <dave@sherohman.org>]

So, after my last message, I ran across a general mdadm setup guide at
https://raid.wiki.kernel.org/index.php/Setting_up_a_(new)_system
and, in the "booting" section of that document, it said to add
GRUB_CMDLINE_LINUX="domdadm"
to /etc/default/grub.  Didn't have that, so I added it, did the checks
mentioned in the document, and reinstalled grub to both EFI partitions.

Still didn't work.

Then I found https://linoxide.com/linux-how-to/grub-rescue-commands/ and
was able to start the installed kernel with the command sequence:

set root=(md/1)
linux (md/1)/vmlinuz root=/dev/md1
initrd (md/1)/boot/initrd.img-4.19.0-14-amd64
insmod normal
boot

This still ultimately died with an error saying the EFI partition had an
"Invalid FSINFO signature".  Searches on that phrase mostly seemed to
talk about secure boot problems, so I double-checked the bios options
and secure boot was off, so that wasn't it.

So I went back to the linoxide.com document and went through all the
steps that I hadn't already done manually:  Running os-prober and
update-grub.  Then grub-install to the EFI partitions again, reboot,
and... success!


Based on this, I'm guessing that the original problem was that the
installer forgot to include mdadm support in its grub options, even
though it was configured with an mdadm boot device.  And then I missed a
couple steps after adding mdadm support, so it didn't all get installed
to the EFI partitions correctly.

-- 
Dave Sherohman