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Upgrading RedHat 6.x to 7.y

by on July 20, 2016

Bottom line

I did it!!

My recommendation

Don’t do it…





And the story goes like this:

Our application is based on a cluster of Hadoop, installed with HortonWorks distribution.
One of the customers is going to start with Version X and then sometime upgrade to Version X+1. These version requires to change the platform matrix: from HDP 2.2 to HDP 2.3 or 2.4 and from RHEL 6.5 to RHEL 7.1.

Checking with the Vendor they gave us recommendation to upgrade first the Hadoop cluster, and then upgrade the OS.

Checking with their competitor Vendor, they specifically do not recommend and upgrade of OS and prefer a fresh installation of RHEL 7.1.

Checking with RedHat they say that it is doable, but they give a long list of constraints.

So i started to check it on some VMs we had.

Following instruction from here –

First obstacle

I have to have IT to give me access to the various channels required.
It took them some time but they did mange to give it to me.

Second obstacle

Red-Hat version (6.5 Vs 6.7).
in the above instruction the first stage is to update all packages of the SO to the latest, i.e.

yum update -y

meaning to upgrade to RHEL 6.7

IT gave me access to local channels with 6.5 only. I did not notice at first, and it can be done afterwards. no harm done.

Third obstacle

Installing the pre-upgrade utility. Should be simple:

yum -y install preupgrade-assistant preupgrade-assistant-ui preupgrade-assistant-contents

But I failed with missing rpms – mainly openscap. it was not missing, but there was a mismatch between the versions of i686 and x86_64.

After a long battle, I found a site to download openscap with the lower version and I’ve installed the rpms locally.


Only after installing the above rpms, with this exact version, and I tried a few others, did I manage to install the pre-upgrade tool and run it.

Forth obstacle

Output of the pre-upgrade utility itself.

It gave many warnings that are need to be checked and only a few FAILs that has to be resolved.

One of the error was that I had the wrong OS flavor – as I did not upgrade to 6.7. I managed to do it with out IT help, using rhel67.iso file that I had.

Another was about the /usr directory, which cannot reside on separate FS because of some changes done in RHEL 7.1.

Other issues related to eth naming convention (and good that this is just a VM with single network link and not a physical server…)

and a few others issues – some look more important than others, but none are show stoppers.

One of the “funny” issues is that there are many rpms installed that are not signed by RHEL. When i look at the list, most, if not all of them, are Hadoop related rpms…

Running the upgrade

RedHat warns in their instructions that it may take a long time, but in my small VM it was actually very fast, and even the reboot brought the VM alive with no issues.

Fifth obstacle

Let the fun begin.
The VM is connected to the Hadoop cluster, meaning that ambari-agent is running OK.
But no other process of Hadoop is willing to start.

To Be Continued…


From → Work in Progress

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