Learning AlmaLinux - ELevate & Cross-Version Migration

#Introduction

In the previous episode, Episode 19, we took AlmaLinux to the cloud, WSL, and Raspberry Pi. Now we cover one of the features that most distinguishes AlmaLinux from other distros: migration. For enterprise admins, a major upgrade usually means a complete reinstall — hours of downtime, reconfiguration, and high risk. AlmaLinux changes that.

This episode covers ELevate for in-place upgrades between major versions, almalinux-deploy for converting from CentOS, and safe migration practices: preflight, rollback, and verification.

#The In-Place Migration Concept

In-place migration means the system is upgraded from an old version to a new one without reinstalling — all packages, configuration, users, and data are kept on the same disk. This contrasts with reinstallation, which starts from scratch.

sudo dnf5 upgrade, which we covered in episode 4, handles minor upgrades within the same major version. To jump major versions (for example 8 to 9, or 9 to 10), a special tool is needed: ELevate.

#ELevate: Upgrading Across Major Versions

ELevate is AlmaLinux's official migration tool based on leapp — the in-place upgrade framework developed by Red Hat. Leapp works by analyzing the system, identifying problems, and performing the upgrade in stages.

#ELevate Workflow

Preflight (risk analysis)
    -> Install leapp + AlmaLinux plugin
    -> Run upgrade phase 1
        -> Reboot into upgrade initramfs
            -> Upgrade phase 2 (system is transformed)
                -> Reboot into the new system

Leapp performs the transformation in two phases with a reboot in between — that's what makes a major upgrade possible without reinstallation.

#Practice: Upgrading 9 to 10

sudo dnf5 install -y leapp-upgrade almalinux-elevate

Once the packages are installed, run the preflight:

sudo leapp preupgrade

After all preflight issues are resolved, run the main upgrade:

sudo leapp upgrade

This command prepares the upgrade and automates the reboot. The system boots into the upgrade initramfs, runs the transformation, then reboots into AlmaLinux 10. The process takes several tens of minutes — and during that time the system must not be interrupted.

#Verifying After the Upgrade

cat /etc/os-release
dnf5 --version
uname -r

These three commands confirm the system really switched: version identity, package manager, and kernel.

#Requirements and Risks

A major upgrade isn't without risk. Before starting, make sure:

• Full snapshot/backup — an in-place upgrade changes many packages at once.
• Enough free disk — leapp needs space for new packages and the initramfs.
• Test in staging first — duplicate the system in a VM, upgrade, and validate before touching production.
• Services stopped safely — the upgrade runs with the system offline (reboot in the middle of the process).

df -h /
dnf5 history list | head

If the disk is nearly full or there are unrecognized custom packages, handle those first — don't start an upgrade in a vulnerable state.

#almalinux-deploy: Converting CentOS to AlmaLinux

For servers still running CentOS, almalinux-deploy performs a direct conversion without reinstallation.

#CentOS 7 to AlmaLinux 8

CentOS 7 (old) is converted to AlmaLinux 8:

wget https://raw.githubusercontent.com/AlmaLinux/almalinux-deploy/master/almalinux-deploy.sh
sudo bash almalinux-deploy.sh

This script replaces the CentOS repositories with AlmaLinux's and upgrades the packages. After it finishes, reboot and verify.

#CentOS 8 and 9 to AlmaLinux

CentOS 8 and 9 can be converted directly via dnf — because both share the same structure as RHEL 8/9. The basic steps replace the repositories with AlmaLinux's then upgrade:

sudo dnf5 swap centos-repos almalinux-repos
sudo dnf5 distro-sync

The combination of swap (swapping repositories) and distro-sync (aligning packages with the new repos) turns CentOS into AlmaLinux at the same version — a far simpler path than cross-major-version conversion.

#Safe Migration Practices

Let's assemble the correct migration procedure for any scenario:

#1. Preflight Check

• Full backup or snapshot.
• Verify disk and resources are sufficient.
• Run leapp preupgrade (for ELevate) and fix all inhibitors.
• Remove packages and config unsupported by the new version.

#2. Rollback Plan

• Prepare a snapshot as a rollback point.
• Note important package versions and changed configuration.
• Test the restore procedure in a lab — don't assume a snapshot works without ever trying it.

#3. Post-Migration

• Reboot and verify cat /etc/os-release.
• Confirm all repositories are active with dnf5 repolist.
• Check SELinux contexts — migrated files sometimes carry old labels:

sudo restorecon -Rv /var /etc /home
sudo ausearch -m avc -ts recent | head

• Run dnf5 upgrade to make sure the system is fully up to date.
• Test all critical services one by one.

#Common Pitfalls

1. Skipping preflight. leapp preupgrade exists to save you — ignored issues will surface in the middle of the upgrade.
2. Migrating without a snapshot. An in-place upgrade changes hundreds of packages; without a rollback point, an error means reinstall.
3. Ignoring custom repos. Third-party repositories are often incompatible across major versions — clean them up before migrating.
4. Forgetting to check SELinux contexts. Always restorecon and check ausearch after migration.
5. Migrating production without a staging test. The process can fail in unexpected ways — test on a system duplicate first.

#Conclusion

In this episode 20 you've mastered cross-version migration: the in-place upgrade concept, leapp-based ELevate for major version jumps, CentOS 7/8/9 conversion with almalinux-deploy and dnf5 swap, and the preflight check, rollback plan, and post-migration verification practices including SELinux contexts.

Key takeaways:

• ELevate enables 8→9 and 9→10 in-place upgrades based on leapp.
• leapp preupgrade is a mandatory step — fix all inhibitors before leapp upgrade.
• almalinux-deploy converts CentOS 7 → AlmaLinux 8; dnf5 swap + distro-sync handles CentOS 8/9.
• Snapshot is the safety net; always test the rollback procedure.
• Post-migration: verify os-release, repolist, restorecon, and upgrade again.
• Migration is a measured process — not a reckless act.

Controlled migration makes you ready to look at this distro's future. In the next episode, Episode 21, we'll cover AlmaLinux 10, Lifecycle & Roadmap — the RHEL 10-based AlmaLinux 10 features, Full Support until 2031 and Maintenance until 2035, the minor release cycle, and the roadmap direction toward image mode and cloud-native. See you there!