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Chapter 2. Planning an upgrade

An in-place upgrade is the recommended and supported way to upgrade your system to the next major version of RHEL.

You should consider the following before upgrading to RHEL 8:

  • Operating system - The operating system is upgraded by the Leapp utility under the following conditions:

    • The Server variant installed of the latest available RHEL 7 version, which currently is:

      • RHEL 7.9 on the 64-bit Intel, IBM POWER 8 (little endian), and 64-bit IBM Z architectures and, when on SAP HANA, on the 64-bit Intel architecture

      • RHEL 7.6 on architectures that require kernel version 4.14: IBM POWER 9 (little endian) or 64-bit IBM Z (Structure A)

        Note

        The IBM POWER 9 (little endian) and 64-bit IBM Z (Structure A) architectures have reached end of life. The final upgrade path for these architectures is from RHEL 7.6 to RHEL 8.4. Subsequent releases to the in-place upgrade, including new upgrade paths, features, and bug fixes, will not include these architectures.

        See Supported in-place upgrade paths for Red Hat Enterprise Linux for more information.

    • Minimum hardware requirements for RHEL 8 met
    • Access to up-to-date RHEL 7.9 and the target OS version (for example, RHEL 8.6) content provided; see Preparing a RHEL 7 system for the upgrade, step 1 for details.
  • Applications - You can migrate applications installed on your system using Leapp. However, in certain cases, you have to create custom actors, which specify actions to be performed by Leapp during the upgrade, for example, reconfiguring an application or installing a specific hardware driver. For more information, see Handling the migration of your custom and third-party applications. Note that custom actors are unsupported by Red Hat.

  • Security - You should evaluate this aspect before the upgrade and take additional steps when the upgrade process completes. Consider especially the following:

    • Before the upgrade, define the security standard your system needs to comply with and understand the security changes in RHEL 8.
    • During the upgrade process, the Leapp utility sets SELinux mode to permissive.
    • In-place upgrades of systems in FIPS mode are not supported.
    • After the upgrade is finished, re-evaluate and re-apply your security policies. For information about applying security policies that have been disabled during the upgrade or newly introduced in RHEL 8, see Applying security policies.
  • Storage and file systems - You should always back up your system prior to upgrading. For example, you can use the Relax-and-Recover (ReaR) utility, LVM snapshots, RAID splitting, or a virtual machine snapshot.
  • High Availability - Upgrades of systems using the High Availability add-on are unsupported.
  • Downtime - The upgrade process can take from several minutes to several hours.
  • Satellite - If you manage your hosts through Satellite, you can upgrade multiple hosts simultaneously from RHEL 7 to RHEL 8 using the Satellite web UI. For more information, see Upgrading Hosts from RHEL 7 to RHEL 8.
  • SAP HANA - If you are using SAP HANA, follow How to in-place upgrade SAP environments from RHEL 7 to RHEL 8 instead. Note that the upgrade path for RHEL with SAP HANA might differ.
  • Public clouds - The in-place upgrade is supported for on-demand Pay-As-You-Go (PAYG) instances on Amazon Web Services (AWS) and Microsoft Azure with Red Hat Update Infrastructure (RHUI). The in-place upgrade is also supported for Bring Your Own Subscription instances on all public clouds that use RHSM for a RHEL subscription.
  • Language - All Leapp reports, logs, and other generated documentation are in English, regardless of the language configuration.
  • Bootloader - It is not possible to switch the bootloader from BIOS to UEFI on RHEL 7 or RHEL 8. If your RHEL 7 system uses BIOS and you want your RHEL 8 system to use UEFI, perform a fresh install of RHEL 8 instead of an in-place upgrade. For more information, see Is it possible to switch the BIOS boot to UEFI boot on preinstalled Red Hat Enterprise Linux machine?

  • Known limitations - Notable known limitations of Leapp currently include:

    • Encryption of the whole disk or a partition, or file-system encryption currently cannot be used on a system targeted for an in-place upgrade.
    • No network-based multipath and no kind of network storage mount can be used as a system partition (for example, iSCSI, or NFS).
    • The in-place upgrade is currently unsupported for on-demand PAYG instances on the remaining Public Clouds (Huawei Cloud, Alibaba Cloud, Google Cloud) that use Red Hat Update Infrastructure but not Red Hat Subscription Manager (RHSM) for a RHEL subscription.

See also Known Issues.

You can use Red Hat Insights to determine which of the systems you have registered to Insights is on a supported upgrade path to RHEL 8. To do so, navigate to the respective Advisor recommendation in Insights, enable the recommendation under the Actions drop-down menu, and inspect the list under the Affected systems heading. Note that the Advisor recommendation considers only the RHEL 7 minor version and does not perform a pre-upgrade assessment of the system. See also Advisor Service Recommendations.