Where are session data stored in PHP, on the hard drive or in memory?

Session data in PHP can be stored either on the hard drive or in memory, depending on the configuration set in the php.ini file. By default, PHP stores session data on the server's hard drive in a specified directory. However, for better performance, especially in high-traffic websites, you can configure PHP to store session data in memory using a caching system like Memcached or Redis. To store session data in memory using Memcached, you need to have Memcached installed and running on your server. Then, you can configure PHP to use Memcached as the session handler by setting the session.save_handler and session.save_path directives in the php.ini file.

// Set session save handler to Memcached
ini_set('session.save_handler', 'memcached');

// Set the Memcached server and port
ini_set('session.save_path', 'tcp://127.0.0.1:11211');

// Start the session
session_start();

// Now session data will be stored in memory using Memcached