If you're still running a CentOS Linux 8 (or earlier) server, migrating to AlmaLinux or Rocky Linux is strongly recommended given CentOS Linux's end of life. This guide covers both the in-place migration approach and the safer fresh-install alternative.
Why Migrate
CentOS Linux 8 reached end of life in December 2021, meaning no further security updates — continuing to run it exposes your server to unpatched vulnerabilities indefinitely.
Two Migration Approaches
| Approach | Pros | Cons |
|---|---|---|
| In-place migration script | No downtime for data transfer, faster | Carries forward any existing system issues/cruft |
| Fresh install + data migration | Clean slate, more reliable long-term | Requires more manual work and planning downtime |
Recommended Approach: Fresh Install (More Reliable)
For production systems, a fresh install with careful data migration is generally the more reliable long-term choice, avoiding any accumulated configuration drift or edge cases the in-place script might not perfectly handle.
Fresh Install Migration Steps
Step 1 — Provision a New AlmaLinux/Rocky Linux VPS
See How to Get Started with AlmaLinux/Rocky Linux on a VPS.
Step 2 — Document Your Current CentOS Server's Configuration
rpm -qa > installed-packages.txt
cp -r /etc/nginx /backup/
cp -r /etc/httpd /backup/
crontab -l > crontab-backup.txtStep 3 — Install Equivalent Software on the New Server
Install matching versions of your web server, database, and runtime using this knowledge base's AlmaLinux/Rocky Linux guides.
Step 4 — Migrate Databases
mysqldump -u root -p --all-databases | gzip > backup.sql.gz
scp backup.sql.gz user@NEW_SERVER_IP:/tmp/
gunzip -c /tmp/backup.sql.gz | mysql -u root -pStep 5 — Migrate Application Files
rsync -avz /var/www/ user@NEW_SERVER_IP:/var/www/Step 6 — Test Thoroughly Before Cutover
Follow the same testing-before-DNS-cutover approach covered in How to Migrate a Full VPS to a New Provider.
Step 7 — Update DNS
See How to Migrate DNS to a New Provider Without Downtime for the low-downtime technique.
In-Place Migration (Alternative, Faster but Riskier)
Both AlmaLinux and Rocky Linux provide official migration scripts that convert an existing CentOS installation without a full reinstall. Given the risk of an in-place conversion on a production system, this approach is best reserved for non-critical systems, or attempted first on a test/staging clone of your production server.
Always take a full snapshot/backup before attempting an in-place migration, regardless of which official tool you use — see Backup Strategy 101: The 3-2-1 Rule Explained.
Post-Migration Checklist
- Verify all services start correctly and function as expected
- Confirm firewalld rules match your intended configuration (not just carried-over iptables rules)
- Check SELinux status and address any new context-related issues — see Understanding SELinux Basics on AlmaLinux/Rocky Linux
- Update any internal documentation referencing the old OS/package manager commands
- Set up automatic security updates on the new system
Common Errors
Services fail to start after in-place migration — review migration script logs carefully; some manually-installed or third-party packages may not migrate cleanly and require reinstallation.
SELinux denials appear that weren't present on CentOS — if CentOS was previously running in permissive mode or with SELinux disabled, moving to a properly enforcing AlmaLinux/Rocky Linux system will surface these; address them via correct contexts rather than disabling SELinux.
Continue Reading
- How to Get Started with AlmaLinux/Rocky Linux on a VPS
- How to Migrate a Full VPS to a New Provider
- Backup Strategy 101: The 3-2-1 Rule Explained
Browse more articles in AlmaLinux & Rocky Linux.
