CentOS 6 to CentOS 7 upgrade maybe possible ?

[hunter86_bg]

Hey guys,

I have just checked RHEl 7.5 Beta release notes and I noticed something interesting:

In-place upgrade from Red Hat Enterprise Linux 6 to Red Hat Enterprise Linux 7
An in-place upgrade offers a way of upgrading a system to a new major release of Red Hat Enterprise Linux by replacing the existing operating system. To perform an in-place upgrade, use the Preupgrade Assistant, a utility that checks the system for upgrade issues before running the actual upgrade, and that also provides additional scripts for the Red Hat Upgrade Tool. When you have solved all the problems reported by the Preupgrade Assistant, use the Red Hat Upgrade Tool to upgrade the system.

What do you think, is this only a Beta feature?

[scottro]

I'm guessing it is new, and they mention solving all problems before doing upgrade. I wouldn't try it on a production server.

Also, RHEL-7.5 is still BETA itself, correct? Therefore, I would think that this is also beta

[TrevorH]

There's nothing new there, there's been a conversion from RHEL6 to RHEL7 since 7.0. Unfortunately no-one has bothered to look at amending the scripts in the packages to cater for CentOS since 7.0 so it's just as unlikely to work as it does now, sorry.

[j.a.duke]

There's nothing new there, there's been a conversion from RHEL6 to RHEL7 since 7.0. Unfortunately no-one has bothered to look at amending the scripts in the packages to cater for CentOS since 7.0 so it's just as unlikely to work as it does now, sorry.

Trevor,

Can you please clarify? Do you mean that none of the CentOS volunteers have done the work to move this from RHEL or that the “feature” just doesn’t work?

Thanks.

Cheers,
Jon

[TrevorH]

There was work done with the initial 7.0 release and the tool did work at that point though not very well. I believe the number of modifications that were needed was substantial and no-one has stepped up to maintain subsequent versions of the tool as they were released by RH upstream. There have been various attempts and expressions of interest from people to have a go at fixing it but no progress has been made and no workable version exists.

At some point in the various point releases of 6.x and 7.x the tool gradually stopped working properly. First it generated either unbootable systems or ones on which many basic functions were not working. Mostly that seemed to be due to there being higher numbered versions of some packages in CentOS 6 compared to those in 7 - so certain packages were never updated to the el7 versions as yum and all the tools believed that the currently installed el6 version was "newer". It broke little things like yum and even the ability to make SSL connections. I believe more recent updates to 6.x and 7.x have now rendered it useless to the point where it won't even run the first phase at all so it never gets around to killing your system - which I guess is sort of an advance in a way.

[toracat]

More details of what TrevorH mentioned can be found in this wiki article, CentOS Upgrade Tool.