On 10/25/2014 09:40 AM, Timothy Murphy wrote:
I would like to upgrade a CentOS-6.5 home server
to CentOS-7 on a new partition.
What is the simplest way to achieve this?
I would like to be able to boot into either version of CentOS
until I am sure the new version is running OK.
Incidentally, I think most people today must have enough space
on their hard drive to install a new OS on a new partition -
it is surprising that this option never seems to be mentioned
in upgrade documentation.
A couple of observations after doing this:
1. It requires a custom disk layout, but is not particularly hard.
2. AFAIK, you can share your SWAP partition between the two installations.
3. Centos 7 uses grub2 as its boot loader. It is significantly different
from "legacy grub" used in Centos 6 and before.
a. It uses a configuration file that is auto-generated, and not supposed
to be edited.
b. It is capable of finding other installations (including legacy grub
and windows), and creating links to them.
c. 'b' only seems to work IF the other boot partitions are mounted
somewhere in your file tree. What I have done is mount the other
partitions (the /boot partition, if it is on a separate partition,
otherwise /) under /mnt (e.g. /mnt/C6) when you are doing your custom disk
layout. As long as they are mounted somewhere in the file system, grub2
seems to find them OK, and add them to your boot menu. It is apparently
incapable of looking on unmounted partitions and finding Operating Systems
lurking there.
d. grub2 is (theoretically) capable of booting off of LVM (and I have
done so successfully), BUT that capability is disabled and unsupported in
RHEL/Centos 7. You still have to put /boot on a non-LVM partition.
Ted Miller
Elkhart, IN, USA
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