I have a 2-disk software RAID CentOS 6 system that I just installed. When I boot from the disk I get "Error 21" from GRUB. I have run this command on sda and sdb, after booting from the rescue DVD image:
dd if=/dev/sda bs=512 count=1 | xxd
I do see GRUB on both drives. I even ran this command for sda and sdb:
fdisk -l does show sda and sdb as my devices.
So, I believe GRUB is on both disks and that I've got the right device names but when I tell the installer to boot from the local disk I get that error.
When I chroot to /mnt/sysimage everything looks fine.
How can I fix this? Thanks.
Update on Nov. 8, 2016 to provide more info.