Upgrading Oracle Linux 6 to 7

Overview

It is possible to upgrade an Oracle Linux 6 system to Oracle Linux 7.6 under the following conditions:
The system meets the minimum installation requirements for Oracle Linux 7 as described in Chapter 1, System Requirements and Limits.
The Oracle Linux 6 system has been completely updated from the ol6_x86_64_latest channel or ol6_latest repository.
UEK R3 or UEK R4 has been installed on the system to be upgraded and is the default boot kernel. Upgrading from UEK R2 is not supported. Note that the system is upgraded to use the UEK R5 release provided with Oracle Linux 7.6.
Upgrading is supported only for systems that are installed with the Minimal Install base environment. If additional packages are installed from an alternative repository or channel, upgrade might fail or the resulting upgrade might not function as expected. reference: https://docs.oracle.com/en/operating-systems/oracle-linux/7/relnotes7.6/ol7-install.html#ol7-upgrade-ol6

Verifying the system before Upgrade:

# head -1 /etc/*rel*
# uname -r
# sudo grubby --default-kernel

Step 1: Preparing for the Upgrade

01. If you are upgrading a remote system, ensure remote connection through a console such as VNC.
02. Ensure the system backup to avoid any kind of loss such as data, application, configuration, etc.
03. Shut down all production services such as application, database, corn jobs, etc.
04. Disable Secure Boot if it is running.

To check the status of Secure Boot, choose one of the following commands:

Using bootctl status,

# sudo bootctl status

Or using mokutil –sb-state,

# sudo mokutil --sb-state

If Secure Boot is enabled on your system go to the firmware/bios at boot time and disable the option.

05. Verify that the locale is set to en_US.UTF-8.

# cat /etc/sysconfig/i18n

If necessary, edit the file to set the locale accordingly.

LANG=”en_US.UTF-8″

06. If your system has network mounted file systems, unmount them and comment out related entries in the /etc/fstab file.

07. If you installed the yum-plugin-versionlock package, clear any packages with locked versions.

# sudo yum version lock clear

08. Configure Oracle Linux Yum server public repo.

# sudo vim /etc/yum.repos.d/public-yum-ol6.repo

And put the below content for enable public_ol6_latest and public_ol6_addons repository.

[public_ol6_latest]
name=Oracle Linux $releasever Latest ($basearch)
baseurl=http://yum.oracle.com/repo/OracleLinux/OL6/latest/$basearch/
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-oracle
gpgcheck=1
enabled=1

[public_ol6_addons]
name=Oracle Linux $releasever Add ons ($basearch)
baseurl=http://yum.oracle.com/repo/OracleLinux/OL6/addons/$basearch/
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-oracle
gpgcheck=1
enabled=1

09. Obtain the latest Oracle Linux 6 packages.

# sudo yum update

10. If your system is currently registered with ULN or a ULN mirror, unregister the system.
Removing a System From ULN in Oracle Linux check out the link.
Checking Yum Configuration check out the link.

11. Reboot the system.

# sudo reboot

12. Make sure that your system is completely up to date by using the yum update command to update to the latest Oracle Linux 6 release. The system must be subscribed to the ol6_x86_64_latest and ol6_x86_64_addons channels or ol6_latest and ol6_addons repositories to be updated. Install the pre-upgrade utility that reside in the public_ol6_addons repository by default. Location of addon repo is https://yum.oracle.com/repo/OracleLinux/OL6/addons/x86_64/. Install the latest versions of the required upgrade packages:

# sudo yum install openscap redhat-upgrade-tool preupgrade-assistant preupgrade-assistant-el6toel7 preupgrade-assistant-el6toel7-data-0 preupgrade-assistant-tools preupgrade-assistant-ui

In my case, preupgrade-assistant-el6toy el7-data-0 package was not available but it is not inhibited at all.
After installing the redhat-upgrade-tool check the version of this package. The version of this package determines which release the system will upgrade.

redhat-upgrade-tool	OL will be upgrade to
redhat-upgrade-tool-0.7.48-1.0.2.el6.noarch.rpm	allows upgrade only to the system version OL-7.5 Server
redhat-upgrade-tool-0.7.49-1.0.2.el6.noarch.rpm	allows upgrade only to the system version OL-7.5 Server
redhat-upgrade-tool-0.7.51-1.0.2.el6.noarch.rpm	allows upgrade only to the system version OL-7.6 Server
redhat-upgrade-tool-0.7.52-1.0.1.el6.noarch.rpm	allows upgrade only to the system version OL-7.6 Server
redhat-upgrade-tool-0.8.0-4.0.1.el6.noarch.rpm	allows upgrade only to the system version OL-7.6 Server

in my case, my system will upgrade to OL-7.6 for this reason I need OL-7.6 iso file.

Step 2: Upgrading the System

01. Grant root SSH login permissions in the /etc/ssh/sshd_config file.

# PermitRootLogin yes

02. Run the preupg command for pre-upgrade assessments. The following command is only for the physical system not for the Oracle Cloud Infrastructure instance.

# sudo preupg

This process generates a process log, a report, and a file called answerfile.

Analyzing the Leapp Report

The /root/preupgrade/result.html file summarises the issues, identifies potential risks and also suggests the remediation path to the upgrade. Open this analysis report with a browser. The risks are classified as an inhibitor, high, medium, or low. The inhibitor and high risk would prevent an upgrade. Read the file thoroughly and solve the issue accordingly. Without resolving inhibited issues you can not go ahead.

Performing the Upgrade

Choose one out of the three methods described below for performing the upgrade process.

01. Installation repository:

# sudo redhat-upgrade-tool-cli --network 7.6 --instrepo ftp-or-http-url --cleanup-post --debuglog=/tmp/upgrade.log

For example,

# sudo redhat-upgrade-tool-cli --network 7.6 --instrepo http://yum.oracle.com/repo/OracleLinux/OL7/latest/x86_64 --cleanup-post --debuglog=/tmp/upgrade.log

02. Mounted installation media:

# sudo redhat-upgrade-tool-cli --device device_path --cleanup-post --debuglog=/tmp/upgrade.log

Run blkid command and find the mounted iso device path.

# sudo blkid

In my case, /dev/sr0: LABEL=”OL-7.6 Server.x86_64″ TYPE=”iso9660″ this is my iso device. Mount this iso device to /mnt directory.

# sudo mount -r -t iso9660 /dev/sr0 /mnt

Now substitute the device_path with the mounted device path For example,

# sudo redhat-upgrade-tool-cli --device /mnt --cleanup-post --debuglog=/tmp/upgrade.log

If you do not specify the device path, the Red Hat Upgrade Tool scans all mounted removable devices.

03. ISO image:

# sudo redhat-upgrade-tool-cli --iso iso_path --cleanup-post --debuglog=/tmp/upgrade.log

For example,

# sudo redhat-upgrade-tool-cli --iso /soft/iso/ol/OracleLinux-R7-U6-Server-x86_64-dvd.iso --cleanup-post --debuglog=/tmp/upgrade.log

Reboot the system after completing the upgrade process.

# sudo reboot

Monitor the boot progress on the console, while the system is rebooting.

Verifying the system after Upgrade

Query the release doc,

# head -1 /etc/*rel*# uname -r# sudo grubby --default-kernel

Step 3: Completing Postupgrade Tasks

Check this link.

Conclusion

This tutorial helps you How to upgrade your existing Oracle Linux 6 system to 7. If have any queries please comment to us. follow the link to Upgrading Redhat Linux 7 to 8 With Leapp.

References

In this tutorial, I follow the official docs as reference Performing Systems Upgrade With Leapp (Oracle Linux 7).