Docs / Migration Guides / Migrating from CentOS 7 to AlmaLinux 9

Migrating from CentOS 7 to AlmaLinux 9

By Admin · Feb 21, 2026 · Updated Apr 23, 2026 · 4 views · 3 min read

In this article, we'll walk through the complete process of working with centos in a server environment. Understanding almalinux is essential for maintaining a reliable and performant infrastructure.

Prerequisites

  • Sufficient storage on the destination server
  • Access to both source and destination servers
  • Root or sudo access to the server
  • A VPS running Ubuntu 22.04 or later (2GB+ RAM recommended)

Pre-Migration Assessment

Security should be a primary consideration when configuring centos. Always use strong passwords, keep software updated, and restrict network access to only the necessary ports and IP addresses.


# Pre-migration data sync with rsync
rsync -avzP --delete \
  --exclude='/dev' --exclude='/proc' --exclude='/sys' --exclude='/tmp' \
  -e 'ssh -p 22' \
  root@old-server:/ /mnt/migration/

# Final sync with minimal downtime
rsync -avzP --delete \
  -e 'ssh -p 22' \
  root@old-server:/var/www/ /var/www/

Each line in the configuration serves a specific purpose. The comments explain the reasoning behind each setting, making it easier to customize for your specific use case.

Data Transfer Process

When scaling this setup, consider vertical scaling (adding more RAM/CPU) first, as it's simpler to implement. Horizontal scaling adds complexity but may be necessary for high-traffic applications.


# Database migration
# On source server:
mysqldump --single-transaction --routines --triggers --all-databases | gzip > db_backup.sql.gz

# Transfer to destination:
scp db_backup.sql.gz root@new-server:/tmp/

# On destination server:
gunzip < /tmp/db_backup.sql.gz | mysql -u root

Make sure to restart the service after applying these changes. Some settings require a full restart rather than a reload to take effect.

Configuration Migration

The almalinux component plays a crucial role in the overall architecture. Understanding how it interacts with centos will help you make better configuration decisions.


# Pre-migration data sync with rsync
rsync -avzP --delete \
  --exclude='/dev' --exclude='/proc' --exclude='/sys' --exclude='/tmp' \
  -e 'ssh -p 22' \
  root@old-server:/ /mnt/migration/

# Final sync with minimal downtime
rsync -avzP --delete \
  -e 'ssh -p 22' \
  root@old-server:/var/www/ /var/www/

These commands should be run as root or with sudo privileges. If you're using a non-root user, prefix each command with sudo.

DNS Cutover Procedure

Before making changes to the configuration, always create a backup of the existing files. This ensures you can quickly roll back if something goes wrong during the setup process.


# Database migration
# On source server:
mysqldump --single-transaction --routines --triggers --all-databases | gzip > db_backup.sql.gz

# Transfer to destination:
scp db_backup.sql.gz root@new-server:/tmp/

# On destination server:
gunzip < /tmp/db_backup.sql.gz | mysql -u root

The configuration above sets the recommended values for a VPS with 2-4GB of RAM. Adjust the memory-related settings proportionally if your server has different specifications.

Security Implications

When scaling this setup, consider vertical scaling (adding more RAM/CPU) first, as it's simpler to implement. Horizontal scaling adds complexity but may be necessary for high-traffic applications.

Summary

You've successfully configured centos on your VPS. Remember to monitor performance, keep your software updated, and maintain regular backups. If you run into issues, consult the official documentation or open a support ticket for assistance.

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