Chapter 7. Performing the upgrade from RHEL 7 to RHEL 8

Procedure

1. Temporarily set an unlimited amount of opened file descriptors before performing the pre-upgrade phase to prevent a known issue:

   # ulimit -n 16384

   See the Known Issues section for more information.

2. On your RHEL 7 system, start the upgrade process:

   # leapp upgrade --target 8.10

   Note

   If you are using custom repositories from the /etc/yum.repos.d/ directory for the upgrade, enable the selected repositories as follows:

   # leapp upgrade --enablerepo <repository_id1> --enablerepo <repository_id2> …

   If you are upgrading without RHSM or using RHUI, add the --no-rhsm option.

   If you are upgrading by using an ISO image, add the --no-rhsm and --iso <file_path> options. Replace <file_path> with the file path to the saved ISO image, for example /home/rhel8.iso.

   At the beginning of the upgrade process, Leapp performs the pre-upgrade phase described in Reviewing the pre-upgrade report.

   If the system is upgradable, Leapp downloads necessary data and prepares an RPM transaction for the upgrade.

   If your system does not meet the parameters for a reliable upgrade, Leapp terminates the upgrade process and provides a record describing the issue and a recommended solution in the /var/log/leapp/leapp-report.txt file. For more information, see Troubleshooting.

3. Manually restart the system:

   # reboot

   In this phase, the system boots into a RHEL 8-based initial RAM disk image, initramfs. Leapp upgrades all packages and automatically reboots to the RHEL 8 system.

   Alternatively, you can enter the leapp upgrade command with the --reboot option and skip this manual step.

   If a failure occurs, investigate logs as described in Troubleshooting.

4. Log in to the RHEL 8 system and verify its state as described in Verifying the post-upgrade state of the RHEL 8 system.
5. Perform all post-upgrade tasks described in the upgrade report and in Performing post-upgrade tasks. Especially, re-evaluate and re-apply your security policies.
6. In case of upgrading a system that was and will be running in FIPS mode, remove any RHEL 7 kernels. Then, regenerate and otherwise ensure the FIPS compliance of all cryptographic keys. See Locations of cryptographic keys in RHEL 8 for more information.