[CentOS] Upgrade from CentOS6.6 to CentOS 7

Tue Dec 15 17:52:19 UTC 2015
Gordon Messmer <gordon.messmer at gmail.com>

On 12/15/2015 07:17 AM, Traiano Welcome wrote:
> I  see there is some attempt at an upgrade tool available, but it's
> apparently broken:
> https://wiki.centos.org/TipsAndTricks/CentOSUpgradeTool


Using "yum --releasever=7 distro-sync --downloadonly", then switching to 
single-user mode and "yum --releasever=7 distro-sync" you *might* be 
able to do it.  However, you should test this on another system or in a 
virtual host.  I've never done it, and it's highly likely to have problems.

You should be aware that the purpose of the centos upgrade tool is to 
identify and warn the user about known problems with an upgrade. Because 
Anaconda installations are highly customizable, it's impossible for any 
of us to tell you if an upgrade will work.  There are too many things 
that might not on your system, which we have no way of knowing.

I don't know what keeps you from doing a clean install.  Anything I can 
imagine that might convince you that this is a good idea, makes this a 
really bad idea.  If you don't have backups, this is an extremely bad 
idea.  If you're trying to minimize down time or work, this is an 
extremely bad idea.