[CentOS] Booting CentOS 6 with Grub from CentOS 7

Thu Oct 11 19:12:05 UTC 2018
mark <m.roth at 5-cent.us>

Stephen John Smoogen wrote:
> On Tue, 9 Oct 2018 at 21:47, Yves Bellefeuille <yan at storm.ca> wrote:
>> I had CentOS 6 installed on an MBR hard disk. I converted the disk to
>> GPT (with UEFI) and installed CentOS 7 on a new partition.

Um, say *what*?! This wasn't a complete rebuild? Next you'll tell us you
buy hardware from Acme, the company that Wile E. Coyote buys hardware.
> Was CentOS6 bootable after you converted the disk to GPT? My luck with
> getting it to work has not been good as the conversion usually changes
> something very important to the underlying OS which needs a reinstall or a
> bunch of 'fiddling' in rescue mode before I could get it to work at all.
> The EL6 kernel and initrd probably do not have the tools in them to
> deal with a GPT partition. Your 'best' bet is to boot into an EL6 rescue
I think they can. However, several things: what I've had to do on our new
rebranded Supermicro boxen is to go into the BIOS, and tell it *not* to
dual boot (that is, legacy BIOS or UEFI), and *not* legacy, but *only*

I will note that we've been using GPT on secondary drives since we started
buying drives > 2TB, and that's been a number of years now....