Scalability is the new black

Scalability is a desirable property of a system, a network, or a process, which indicates its ability to either handle growing amounts of work in a graceful manner or to be enlarged.

What is scalability?

-Wikipedia

Pressflow

The performance aware and scalable fork of Drupal

Pressflow

ProsDrops support for old PHP versions ( < 5.2 )

Better session handling

Reverse Proxy support

More info: https://wiki.fourkitchens.com/display/PF/Comparison+-+Pressflow+versus+Drupal

Pressflow

ConsLess users => less feedback => more unpredictable behavior

Delay between corresponding prefflow forks and vanilla Drupal

Patch compatibility is not 100% guaranteed

Pressflow

Should I use Pressflow?Yesif you need the features of PF

Pressflow

Should I use Pressflow?Yesif you need the features of PF

Noif you are afraid of experimental and 3rd party code for the site

seixorP esreveR

What is it? Gate keeper / intermediary for incoming requests. Should be able to handle multiple backends with active load balancing. Can act as a caching frontend and a buffer for slow clients.

Reverse Proxies

Notable examplesApache 2 with modules

Squid most used proxy

Varnish mostly used with Drupal sites

Nginx http and proxy server in one

Varnish

ProsHighly recommended from most of the people within the Drupal community

Almost out of the box compatibility with Pressflow (and Drupal 7)

Surpassed only by nginx with a very small margin

Very helpful tools (varnishtop, varnishhist etc)

Varnish

ConsNot as widely used as squid (the defacto standard in proxies)

Configuration looks difficult at first

A little slower than nginx

Needs a backend

Varnish Installation

Debian based distributions# apt-get -t testing install varnish

Configure diffrent listening port for apache if they share the same environment

Configure Varnish to forward traffic to the Apache's server IP and Port

Pressflow Settings

Add the following lines to settings.php

$conf = array( 'reverse_proxy' => TRUE, 'reverse_proxy_addresses' => array( '10.0.0.1', // Reverse proxy host A '10.0.0.2', // Reverse proxy host B '10.0.0.3', // Reverse proxy host C [...] ), );

Enable Drupal's page cache in 'admin/settings/performance' Set the Caching Mode to External Set the Page Cache Maximum Age > 0

Varnish Optimizations

Optimize Apache with only PHP in mind

Static files should have expire headers for correct varnish cache life

Avoid non 2xx request status, like 3xx redirects.

Choose carefully the Minimum cache lifetime in Pressflow

backend default { .host = "