[CentOS] Grub legacy on Centos 7

[Chris Murphy]

On Sun, Aug 16, 2015 at 3:18 PM, Sachin Gupta <sachin3072004 at gmail.com> wrote:
> Hello Everyone,
>
> We have centos6  server. And we are planning to upgrade it to Centos7.And
> GRUB 2 needs a new bios grub partition.

BIOS boot partition is only necessary on GPT partitioned disks. For
MBR partitioned disks, the GRUB 2 core.img goes into the MBR gap, the
same as before. On rare occasion when the 1st partition starts at LBA
63 the core.img can't fit into the gap. The supported work around is
repartitioning such that 1st partition starts at LBA 2048. The less
supported and recommended work around is to use grub2-install with -f


>Creating a new partition is too
> much risky.

It really isn't. You can use gparted to resize/move the /boot
partition/volume safely and fast. And if it blows up just reformat it
it in the installer which isn't a bad idea to do anyway. There's no
need to keep an old CentOS 6 /boot partition around anyway.

>I am wondering if it is possible to replace Grub2 with Grub
> legacy on Centos7 machine?

Yeah just yum erase grub2 and then force the installation of the
CentOS 6 grub package; then run grub-install.

-- 
Chris Murphy