I have a desktop with two disks, both wich Centos 7 backing up each
other. Both disks have Grub2 in the MBR.
On the first disk, in the Grub2 Menu /boot/grub2/grub.conf, I added a
menuentry to chainload the second disk. This chainloader menuentry looks
like:
menuentry '3boot via chainloader from lower disk' {
set root='hd1'
chainloader +1
}
This way I can boot the 2nd disk from the 1st one, and I don't need to
change boot preferences in the BIOS.
suomi
On 2014-08-09 12:23, Alan McRae wrote:
> No problems Joe. I have done this multiple times.
>
> I assume you have Fedora 20 on sda (the first disk) with
> the bootloader (grub2) on sda. Your BIOS will be set to boot sda.
>
> You install CentOS 7 on sdb (obvious).
>
> Your options are with the bootloader (grub2). If you install
> the bootloader on sdb the two systems will remain separate.
> You will have to change the BIOS to boot either sda (F20) or sdb (C7).
>
> The way I prefer would be to install the new bootloader on sda
> (overwriting the current configuration).
> Your BIOS will still boot sda which will take you into
> the grub2 menus which will show both Fedora 20 and CentOS 7.
>
> You need to be aware that in the above configuration sda will
> boot into /boot on sdb (C7) which will have the dual boot menus.
> Don't wreck this directory or you won't be able to boot F20 (easily).
>
> The F20 and C7 installers are very good. They scan the disks for
> linux and Windows installations and add them into the boot menu for you.
>
> I have a laptop which boots C7, C6, F20, XP and 3 versions of Android
> using grub2.
>
> Alan
>
> On 09/08/2014 17:02, Ted Miller wrote:
>> On 07/31/2014 11:37 AM, Joseph Hesse wrote:
>>> Hi,
>>>
>>> I have a laptop with 2 hard drives. The first has Fedora 20 (no windows
>>> or anything else) and the second is unused. I would like to install
>>> CentOS7 on the unused drive so I can dual boot with the choice of the 2
>>> OS's on the Grub menu.
>>> I am comfortable in partitioning drives and installing Linux
>>> distributions. I am afraid I may mess up the MBR and/or set up Grub
>>> incorrectly so I lose everything.
>>>
>>> Please point me to some documentation to help me.
>>>
>>> Thank you,
>>> Joe
>> I see no answers to this, so I will tell you this: If you have a CD (or USB
>> drive) with the Super Grub Disk from www.supergrubdisk.org, you will be
>> able to get to your linux installations no matter how badly you mess up you
>> MBR. It is usually quite difficult to cut yourself off from an existing
>> installation, because usually the new install process will find the old
>> installation and include it on the new menu.
>>
>> Ted Miller
>>
>>
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