[CentOS] GRUB 2 dumps to grub prompt when installed on >4TB disk

Tue Aug 23 17:43:50 UTC 2016
James A. Peltier <jpeltier at sfu.ca>

----- Original Message -----
| On Mon, Aug 22, 2016 at 1:24 PM, James A. Peltier <jpeltier at sfu.ca> wrote:
| >
| >
| > When running grub2-install from within recovery mode I can assure you it is
| > not a user error because simply installing the grub2-efi-modules package
| > allows for grub2-install to work.
| No, this logic is flawed. Running grub2-install is obsolete on UEFI,
| it only applies for users who know exactly what they're getting
| themselves into and have a use case for modules in grub2-efi-modules
| that are not already in the grubx64.efi binary that's included in the
| grub2-efi package. If you run grub2-install, it blows away that
| grubx64.efi from the grub2-efi package in favor of a custom built one,
| which has completely different and for the most part undocumented
| behavior.

Perhaps this should be documented then.  I had assumed (yes, I know) to this working the same on an EFI based system system since apparently this it isn't documented.

| For example the grubx64.efi bootloader in grub2-efi expects to find
| grub.cfg on the ESP in the same directory as the grubx64.efi binary.
| If you run grub2-install, the resulting grubx64.efi expects to find
| grub.cfg in /boot/grub2/ which is on your boot volume, not the EFI
| System Partition. If this is UEFI system with Secure Boot enabled, the
| grub2-install created grubx64.efi is not signed, so it'll fail Secure
| Boot unless you go down the rabbit hole of signing it yourself.
| Whereas the CentOS supplied grubx64.efi in the grub2-efi package is
| already signed. And so on.
| How are you booting the CentOS installation media? How was that media
| created? This matters because it's possible to end up with a CSM-BIOS
| boot inadvertently, and the installer will install a grub for BIOS
| firmware, and not the entirely separate bootloader for UEFI. So it
| might be worth booting from that install media, and get to a shell and
| check if in fact this is an UEFI mode boot by running efibootmgr. If
| you get an error message, it's not a UEFI mode boot, it's using
| CSM-BIOS mode, and that would explain why the wrong bootloader is
| being installed by the installer.

We're doing a pretty standard iPXE/Kickstart installation that has worked on other UEFI based systems R710/720/730, etc based systems.  This is the first system that I've run into this with.  We will try booting the installation media, because we're also including the updates repository as part of the installation and perhaps this is causing the issue.

James A. Peltier
IT Services - Research Computing Group
Simon Fraser University - Burnaby Campus
Phone   : 604-365-6432
Fax     : 778-782-3045
E-Mail  : jpeltier at sfu.ca
Website : http://www.sfu.ca/itservices
Twitter : @sfu_rcg
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