CentOS - Jul 2020 - Not getting bootloader installed with CentOS 8 + mdraid

I am trying to use a kickstart to install CentOS 8.2 on a server with a
pair of drives with Linux software RAID 1.  The install completes, but
the resulting system will not boot - I get "Booting from Hard drive
C:"
from the BIOS (Dell in legacy BIOS mode, not UEFI) and it stops.  If I
then start the installer in rescue mode and run grub2-install on the two
drives, it boots okay.

If I take out the RAID config and just install on the first drive, it
boots fine - it appears to just be an issue with RAID.  I tried my
kickstart in a KVM VM with two disks, and it works there (I get RAID and
a bootloader).

Anybody else run into this?  Any ideas?  I've been installing from
kickstarts for ages, including software RAID, but not CentOS 8 with
software RAID until now.

-- 
Chris Adams <linux at cmadams.net>

Once upon a time, Chris Adams <linux at cmadams.net>
said:
> I am trying to use a kickstart to install CentOS 8.2 on a server with a
> pair of drives with Linux software RAID 1.  The install completes, but
> the resulting system will not boot - I get "Booting from Hard drive
C:"
> from the BIOS (Dell in legacy BIOS mode, not UEFI) and it stops.  If I
> then start the installer in rescue mode and run grub2-install on the two
> drives, it boots okay.
Never mind, this was user error. :)

I have a kickstart that discard unused space in %post to make VM images
smaller, and it tries too hard (and the SSDs listened!) - it got the
unpartitioned space between the partition table and the first partition,
and GRUB2 uses more of that when /boot is on RAID1.  Oops.
-- 
Chris Adams <linux at cmadams.net>