Install and Configure Memcached on Debian or RedHat

Introduction

Memcached is a high-performance, distributed memory object caching system. This guide will walk you through the installation and advanced configuration of Memcached on Debian and RedHat-based systems.

Installation

On Debian

# Update the package database
sudo apt update

# Install Memcached
sudo apt install memcached libmemcached-tools

# Start Memcached
sudo systemctl start memcached

# Enable Memcached to start on boot
sudo systemctl enable memcached

# Check Memcached status
sudo systemctl status memcached

On RedHat

# Enable the EPEL repository
sudo yum install epel-release

# Install Memcached
sudo yum install memcached

# Start Memcached
sudo systemctl start memcached

# Enable Memcached to start on boot
sudo systemctl enable memcached

# Check Memcached status
sudo systemctl status memcached

Basic Configuration

Memcached configuration file is typically located at /etc/memcached.conf. Here are some basic configuration options:

# Set the IP address that Memcached will listen on
-l 127.0.0.1

# Set the port that Memcached will listen on
-p 11211

# Set the maximum memory usage
-m 64

# Set the maximum number of simultaneous connections
-c 1024

Advanced Configuration

Logging

Enable detailed logging for Memcached for monitoring and troubleshooting.

# Enable verbose logging
-vv

# Specify the log file (using a log management tool like syslog is recommended)
# Example for systemd:
# Edit the file /etc/systemd/system/memcached.service.d/override.conf
# Add the following lines:
[Service]
ExecStart=
ExecStart=/usr/bin/memcached -u memcache -m 64 -p 11211 -c 1024 -vv

Security

Securing Memcached involves setting proper access controls and limiting access to trusted networks.

# Listen on a specific IP address (local only or trusted network)
-l 127.0.0.1

# Configure firewall to restrict access to Memcached port (11211)
# Example using iptables:
sudo iptables -A INPUT -p tcp --dport 11211 -s 127.0.0.1 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 11211 -j DROP

# Example using firewalld (RedHat/CentOS):
sudo firewall-cmd --permanent --add-port=11211/tcp --zone=trusted
sudo firewall-cmd --reload

Performance Tuning

Optimize Memcached performance by configuring various parameters.

# Adjust the size of each slab page (default is 1MB)
-I 2m

# Enable large pages support (if supported by the system)
-L

# Adjust the size of the memory chunk allocated for each slab class
--chunk-size 64

# Enable CPU affinity to bind Memcached process to specific CPU cores
-a 1

Monitoring and Statistics

Monitor Memcached performance and usage statistics.

# Enable detailed stats output
-vv

# Use the 'stats' command to get detailed statistics
echo "stats" | nc localhost 11211

# Use the 'stat' command to get stats for specific settings
echo "stats settings" | nc localhost 11211

Conclusion

By following this guide, you should have a well-configured Memcached instance on either Debian or RedHat. Proper configuration and regular maintenance are crucial for leveraging the full potential of Memcached.

LINUXexpert