How to migrate CentOS 7 to Rocky Linux 9

Upgrade CentOS 7 to Rocky Linux 8

Step 1: Create a Backup

Before migrating any system, the best practice is to create backups and snapshots of the system. The exact steps depend on the infrastructure, but a bare-metal restore is recommended. Tools such as the dd command and reliable backup and restore solutions are recommended before moving production systems.

Step 2: Install Migration Packages

Install the required packages for migration. Follow the steps below:

1. Install the elevate-release package from the repository for the latest version. Use the following command:

2. Install the Leapp migration data packages for Rocky Linux and the upgrade utility with the following

The Leapp utility handles OS and application upgrades.

Step 3: Run Pre-Upgrade Checks

Run a pre-upgrade to do a system check before upgrading:

The pre-upgrade takes some time. When completed, it generates files in the /var/log/leapp/ directory that contain all potential upgrade issues and how to address them. The following files contain crucial information:

• answerfile – Contains questions that require a true or false answer to proceed with the upgrade.
• leapp-report.txt – Contains all possible problems and fixes to perform before or after the upgrade.
• leapp-preupgrade.log – The complete pre-upgrade log and debug output.

Check the first two files and perform all required pre-upgrade actions. Some common pre-upgrade fixes when migrating from CentOS 7 are:

1. Removing the pata_acpi kernel module:

2. Updating the SSH config file to permit root login

3. Confirming the removal of the PAM PKCS#11 module

The command updates the answerfile, confirming the removal. Address all fixes and rerun the pre-upgrade command to confirm everything is fixed

The system is ready for upgrade when the “Upgrade Inhibited” message disappears.

Step 4: Run Upgrade When no more suggested actions exist, the system is ready to upgrade. Proceed with the OS upgrade steps below:

1. Run the Leapp upgrade command

Wait for the upgrade to complete. If the upgrade fails, return to the previous step and address any issues missed in the pre-upgrade check.

2. When the process completes successfully, reboot the machine:

The reboot is required for the package-swapping process to begin.

3. 3 The GRUB menu shows a new entry called ELevate-Upgrade-Initramfs.

After five seconds, the system automatically boots into this selection and continues the upgrade process.

4. The system restarts twice more after the upgrades. When the restarts are complete, the GRUB menu shows a Rocky Linux 8 entry.

The entry indicates a successful upgrade from CentOS 7 to Rocky Linux 8. The system automatically boots into the upgraded version.

Step 5: Post-Upgrade Steps

After the upgrade, complete the following post-upgrade tasks:

1. Log in as the root user using the same credentials from the CentOS 7 system.

2. Clean up any orphaned packages from CentOS 7:

The command searches for and removes all unnecessary CentOS packages and may hinder the following upgrade.

Credit : How to Migrate CentOS 7 to Rocky Linux 9 | phoenixNAP KB