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 >> >> >> _______________________________________________ >> CentOS mailing list >> CentOS@centos.org >> http://lists.centos.org/mailman/listinfo/centos > > _______________________________________________ > CentOS mailing list > CentOS@centos.org > http://lists.centos.org/mailman/listinfo/centos > _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos