CentOS - Aug 2018 - Remote update OS from 6 to 7

Hello all...
I have a remote machine running C6. I desire to update it to C7. Not
possible to be on-site. Can I copy the Everything ISO for C7 to the
machine,
mount -o loop C7.Everything.iso  /media/cdrom

then do a "yum upgrade" ?

Will that work? The server is using software raid.

Thanks

Jerry

On 29/08/2018 13:24, Jerry Geis wrote:
> Hello all...
> I have a remote machine running C6. I desire to update it to C7. Not
> possible to be on-site. Can I copy the Everything ISO for C7 to the
> machine,
> mount -o loop C7.Everything.iso  /media/cdrom
>
> then do a "yum upgrade" ?
>
> Will that work? The server is using software raid.
>
> Thanks
>
> Jerry
>
I've seen many comments discouraging trying to do this, let alone trying 
to do it remotely (and I assume you don't have IPMI, iLO or other 'bare 
metal' remote acess).

However, the process does not involve yum upgrade, you can check the 
following link which seems to go through the process in detail:

https://shaunfreeman.name/blog/upgrading-centos-6-5-to-centos-7-2

Be sure to complete the backup, and be ready to travel to site, or have 
remote-hands to restore the backup should the process go wrong.

Best Practice would be to configure a new Centos 7 system, and ship it 
pre-configured ready for a data transfer and migration of service to the 
new system, the decomission the old system and have it sent back to you.

Hi, Jerry,

Jerry Geis wrote:
> I have a remote machine running C6. I desire to update it to C7. Not
> possible to be on-site. Can I copy the Everything ISO for C7 to the
> machine, mount -o loop C7.Everything.iso  /media/cdrom
>
> then do a "yum upgrade" ?
>
> Will that work? The server is using software raid.
Not a good idea. Here's a better one, that we've used here: ideally from
another system running C7 that's the same hardware (otherwise, you need to
rebuild the initrd).
mkdir /new /boot/new
rsync -HPavzx --exclude=/old --exclude=/var/log/wtmp $machine:/. /new/.
rsync -HPavzx $machine:/boot/. /boot/new/.

After the copy, check these files:

/boot/new/grub/device.map - should list the correct device name for hd0
/new/etc/fstab - should have the correct labels for file systems
Do this, too:
rsync -HPavzx /etc/sysconfig/network-scripts/ifcfg-eth*
/new/etc/sysconfig/network-scripts
rsync -HPavzx /etc/sysconfig/hwconf /new/etc/sysconfig
rsync -HPavzx /boot/grub/device.map /boot/new/grub/
rsync -HPavzx /etc/udev/rules.d/70-persistent-net.rules
/new/etc/udev/rules.d/

on the new machine, run

 find /new/var/log/ -type f -exec cp /dev/null {} \;

f this system is using Linux RAID,

 rsync -HPavx /old/etc/md.conf /etc/

Copy the original SSH keys:

rsync -HPavzx /etc/ssh/ssh_host* /new/etc/ssh

Finally, rotate:
zsh
zmodload zsh/files

cd /boot
mkdir old
mv * old
mv old/lost+found .
mv old/new/* .

# Root partition.
cd /
mkdir old
mv * old
mv old/lost+found .
#mv old/root . -- WHY?
mv old/scratch .
mv old/new/* .

sync
sync

Make selinux reset all the security file labels

touch /.autorelabel

Reboot, and when it comes back up, rerun grub2-install....

   mark