Setting Up and Using Memcached on VPS: A Comprehensive Guide

When your website or application starts to experience higher traffic, caching becomes a critical performance optimization tool. Memcached is one of the most popular and efficient (เช่า VPS) caching systems available. By storing frequently accessed data in memory, Memcached can significantly reduce the load on your database, speed up page load times, and enhance the overall performance of your site or application.

In this article, we’ll walk you through setting up and using Memcached on your VPS for improved performance, including installation, configuration, and best practices to maximize its potential.

What is Memcached?
Memcached is an open-source, distributed memory object caching system. It is designed to cache data in RAM, making it extremely fast compared to traditional database queries or disk-based storage. Memcached can cache a variety of data types, including:

Database query results: Storing the result of a query to avoid querying the database repeatedly.
API call responses: Caching responses to API calls to minimize repeated processing.
Page fragments: Caching sections of a webpage to reduce the server-side rendering load.
Session data: Storing user sessions in memory for faster access.
By using Memcached, you can offload expensive operations and provide faster responses to your users, which is especially important for high-traffic websites or applications.

Why Use Memcached on Your VPS?
Using Memcached on your VPS can have several advantages:

Improved Performance: By reducing database calls and computations, Memcached can significantly speed up the response times of your site or app.
Reduced Database Load: Memcached stores data in memory, reducing the number of direct queries to the database, which can help in optimizing resource usage.
Scalability: Memcached can scale with your needs. As traffic increases, you can add more memory to your VPS or use additional nodes to scale the caching system.
Now that we understand why Memcached is important, let’s walk through the steps for setting it up on your VPS.

Step 1: Installing Memcached on Your VPS
Before setting up Memcached, make sure your VPS is running an updated version of your preferred Linux distribution (Ubuntu, CentOS, Debian, etc.).

On Ubuntu/Debian
Update System Packages:

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sudo apt update && sudo apt upgrade
Install Memcached: Memcached is available in the default repositories for most Linux distributions, so you can install it using the package manager:

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sudo apt install memcached libmemcached-tools
Start Memcached: After the installation, Memcached should start automatically. If not, use the following command to start it:

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sudo systemctl start memcached
Enable Memcached to Start at Boot: To ensure Memcached starts automatically when your server reboots, run:

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sudo systemctl enable memcached
On CentOS/RHEL
Install Memcached:

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sudo yum install memcached libmemcached
Start and Enable Memcached:

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sudo systemctl start memcached
sudo systemctl enable memcached
Check Memcached Status: Verify that Memcached is running:

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sudo systemctl status memcached

Step 2: Configuring Memcached for Optimal Performance
Once Memcached is installed, it’s important to configure it to handle your application’s needs efficiently.

1. Adjusting Memory Allocation
By default, Memcached allocates 64 MB of memory, which may not be sufficient for heavy workloads. You can increase the memory allocation by editing the Memcached configuration file.

Edit the Memcached Configuration File:

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sudo nano /etc/memcached.conf
Increase the Memory Allocation: Find the line starting with -m (memory allocation) and increase the value based on the available RAM on your VPS:

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-m 2048
This example allocates 2GB of memory to Memcached.

Save and Exit: Save the file (Ctrl + X, then Y to confirm) and restart Memcached to apply the changes:

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sudo systemctl restart memcached

2. Configuring the Binding IP Address
By default, Memcached binds to localhost (127.0.0.1), which means it can only be accessed locally. If you need Memcached to be accessible from other servers, you can change the binding IP address.

Edit the Memcached Configuration File:

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sudo nano /etc/memcached.conf
Update the Bind Address: Find the line that reads -l 127.0.0.1 and replace it with the IP address of your VPS or 0.0.0.0 for all IP addresses:

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-l 0.0.0.0
Restart Memcached: Apply the changes by restarting Memcached:

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sudo systemctl restart memcached

3. Securing Memcached
Memcached is often targeted by attackers for DDoS attacks or unauthorized access. You can secure your Memcached installation by using firewall rules and requiring a password for access.

Restrict Access Using a Firewall: You can use a firewall like UFW (on Ubuntu) or firewalld (on CentOS) to limit access to Memcached:

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sudo ufw allow from <your-IP> to any port 11211
Set a Password for Memcached (optional): Add the following to your Memcached configuration file to set a password:

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-P /path/to/memcached.pid
-u memcache

Step 3: Integrating Memcached with Your Application
Memcached works by storing key-value pairs in memory. To take advantage of Memcached, you need to integrate it with your application’s code.

1. Using Memcached with PHP
If you’re using PHP, the memcached extension is required. You can install it using:

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sudo apt install php-memcached
Then, use the following PHP code to interact with Memcached:

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$mem = new Memcached();
$mem->addServer('localhost', 11211);

$key = "user_data";
$value = array("name" => "John Doe", "email" => "[email protected]");

// Store the value in Memcached
$mem->set($key, $value);

// Retrieve the value
$data = $mem->get($key);
print_r($data);

2. Using Memcached with Python
For Python applications, you can use the pylibmc library to interact with Memcached. Install it using pip:

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pip install python-memcached
Then, you can use the following Python code to work with Memcached:

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import memcache

client = memcache.Client([('localhost', 11211)], debug=1)

# Storing data
client.set("key", "value")

# Retrieving data
value = client.get("key")
print(value)
Best Practices for Using Memcached
Eviction Policies: Memcached uses an eviction policy to remove the least recently used (LRU) items when the cache is full. Be sure to choose an eviction policy that suits your needs.
Data Expiry: Set an expiration time for cached data to avoid stale information.
Monitor Performance: Regularly monitor Memcached’s performance with tools like memcached-tool or using server monitoring solutions to identify memory usage and cache hits/misses.