Upgrade from CentOS 6 to CentOS 7

Installing Redhat upgrade tool:

 

redhat-upgrade-tool is not available on standard repositories, you must set up the repository to install it.

# vi /etc/yum.repos.d/upgrade.repo

 

Place the following entries in it.

[upgrade]
name=upgrade
baseurl=http://dev.centos.org/centos/6/upg/x86_64/
enabled=1
gpgcheck=0

 

Install the following packages.

# yum -y install preupgrade-assistant-contents redhat-upgrade-tool preupgrade-assistant

 

PreUpgrade Assistant:

 

Run the following command to check the potential problem you might encounter with an upgrade from CentOS 6 to CentOS 7 before making a changes to the system.

# preupg

 

Note:

The output of preupg command has been shorted to reduce the length of the post.

 

Perform upgrade:

 

We are going to use the repo file for the upgrade, issue the following command to import the GPG key.

# rpm --import http://centos.excellmedia.net/7.0.1406/os/x86_64/RPM-GPG-KEY-CentOS-7

 

As per the man page, the following command is used to upgrade the CentOS 6; this will download the packages from the internet.

# redhat-upgrade-tool --network 7.0 --instrepo http://centos.excellmedia.net/7.0.1406/os/x86_64/

 

This may result in an error:

 setting up repos...
.treeinfo                                                                                                                                        | 1.1 kB     00:00
preupgrade-assistant has not been run.
To perform this upgrade, either run preupg or run redhat-upgrade-tool --force 

 

So,  re-run the  redhat-upgrade-tool with the –force option (not recommended, but this is only solution as of now)

# redhat-upgrade-tool --network 7.0 --force --instrepo http://centos.excellmedia.net/7.0.1406/os/x86_64/

 

On finish, Reboot to start upgrade.

# reboot

 

Upgrade toCentOS 7:

 

The server will boot with the redhat-upgrade-tool kernel to upgrade the CentOS 6, now you can find the up-gradation activity via console.

Now you can see the installation of the packages.

Once completed, you will get the login screen.

 

Verify using the following command.

# cat /etc/redhat-release
CentOS Linux release 7.0.1406 (Core)

 

That’s All!

 

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