How to Install Virtualmin with Multiple PHP and MySQL Versions on CentOS 8

Deploying a production web hosting stack on CentOS 8 with Virtualmin requires modern multi-PHP support (allowing legacy applications to run PHP 5.6 or 7.2 while modern apps run PHP 7.4 or 8.0) and reliable database server management via Remi repositories.

Stack: CentOS 8 • Virtualmin 6.x • Remi Software Collections (SCL) • MySQL 8.0 • Multi-PHP

1. Fix Perl UTF-8 Locale Warnings

cat << 'EOF' > /etc/environment
LANGUAGE=en_US.utf8
LC_ALL=en_US.utf-8
LANG=en_US.utf8
LC_TYPE=en_US.utf8
EOF

2. Enable EPEL and Remi Repositories

dnf install epel-release -y
dnf install https://rpms.remirepo.net/enterprise/remi-release-8.rpm -y
dnf module reset php -y
dnf module enable php:remi-7.4 -y

3. Installing Parallel PHP Versions

dnf install php56-php-fpm php72-php-fpm php74-php-fpm php80-php-fpm -y

4. Install Virtualmin

wget http://software.virtualmin.com/gpl/scripts/install.sh
sh install.sh

Linux Server Performance Tuning: Reducing Disk I/O and System Load

When optimizing a high-traffic dedicated Linux server, disk I/O bottlenecks are often the primary cause of sluggish response times and elevated load averages. Here are several practical server-tuning techniques I applied to a heavily loaded production server, resulting in a dramatic reduction in disk I/O and much faster throughput.

Key Optimizations: RAM-backed /tmp mount • Dedicated SSD for MySQL data • FastCGI process management with Nginx + PHP-FPM

1. Mount /tmp as a Ramdisk (tmpfs)

Many web stacks heavily utilize /tmp for transient disk writes:

• PHP Sessions: Default PHP configurations store active session files in /tmp (session.save_path).
• MySQL Temporary Tables: Heavy queries with extensive JOIN or GROUP BY clauses frequently write temporary on-disk tables to /tmp (verify your path using mysqladmin variables | grep tmpdir).

Mounting /tmp directly into RAM eliminates spinning disk access for these operations. Add the following entry to your /etc/fstab:

none /tmp tmpfs nr_inodes=200k,mode=01777,nosuid,nodev 0 0

Remount or apply without rebooting:

mount -o remount /tmp

2. Isolate MySQL Datadir to High-Performance Storage (SSD)

Moving the MySQL database directory (/var/lib/mysql) to dedicated high-speed SSD storage removes the database write bottleneck and dramatically lowers IO wait times (%iowait) during peak traffic.

3. Adopt Nginx with PHP-FPM

Switching from Apache's traditional prefork MPM / mod_php handler to Nginx + PHP-FPM significantly cuts memory footprint per connection, handles concurrency gracefully, and frees up system resources for database caching.