RHEL 6.10 to 7.6 OS upgrade using redhat-upgrade-tool

//Pre-requisites

Complete backup has to done before.

OS need to be registered with Redhat subscription.

Rhel 6.10, Rhel 7.6 iso images.

//Steps

complete backup to the server first

make sure the current running OS version is latest on their serious for 6 it should be 6.10.

# yum update // here it will upgrade the subversion if not latest.

# reboot

# cat /etc/redhat-release //check twice with this yum update -y make sure all package are up-to-date

Need to install pre-upgrade assistant tool and enable extra repository

# subscription-manager repos --enable rhel-6-server-extras-rpms

# yum install preupgrade-assistant preupgrade-assistant-el6toel7

# preupg -v //run this tool

// this output will be saved in /root/preupgrade/result.html we can check their upgrade status

// then install upgrade tool

# yum install redhat-upgrade-tool 

// now disable all the current active repositories

# yum -y install yum-utils && yum-config-manager --disable \*

// now execute the upgrade process during the upgrade it requires redhat linux 7 packges, we should need to locally mount the ISO image. please refer the post on this same blog for how to mount the image locally.

# redhat-upgrade-tool --network 7.6 --instrepo //mnt/rhel7iso

# redhat-upgrade-tool --device device_path

// if we don't specify the device path redhat upgrade tool scans all mounted removable location on server

# redhat-upgrade-tool --iso //mnt/rhel7iso

# redhat-upgrade-tool --cleanup-post

# reboot

# rpm -qa | grep .el6 &> /tmp/el6.txt

# rpm -e $(cat /tmp/el6.txt) --nodeps

# yum update //you will get latest package of rhel 7

# reboot

# cat /etc/redhat-release

# yum repolist

//if facing any issue on repolist, need to unsubscribe or clean or resubscription would solve the issue.

# subscription-manager remove --all

# subscription-manager clean

# subscription-manager refresh

# subscription-manager unregister

# subscription-manager register