Server requirement recommendations for your consulting clients

When thinking about the server hardware for a Drupal site, there are two important questions to ask:

1. Which modules are you going to use? Certain modules require more server power than others, but generally speaking more modules means more server requirements.

2. How many users will you have and what will they be doing? More users means more of a demand on the server, but especially if these users login and make comments or nodes you will need a more powerful server.

You need to consider these two answers together. For example, you could have a highly complex site with very few users and be able to use a shared hosting environment. You could also use very few modules, only have one editor, use the cache, and have reasonable traffic on a shared environment.

If your project is a more interactive environment with more users logging in and posting to the site you will need to consider more powerful hardware. As you move out of a shared environment there are other options available to you like using the methods described in the handbook to Tune Your Server for optimal Drupal performance. Tuning the server may allow you to continue using the same hardware and not upgrade, but it comes at the cost of time which can be more expensive than simply buying new hardware.

When deciding which parts of your server to upgrade, remember that "Apache is bandwidth limited, PHP is CPU limited, and MySQL is memory limited and disk I/O bound".

Message to the Client

It's probably best to give the message to the client of a "recommended" installation and a level below that in case their budget is limited and a level above that to provide for future growth with purchasing new hardware and services.

If you are rolling out a new service (as opposed to installing Drupal in place of an existing solution) keep an eye towards a solid upgrade path. You can purchase a single server with the intent of upgrading as your site grows. For example, start with the web server and database on one server that is optimized for web serving. As the site grows in popularity and you need to handle more users you can then move the database to it's own server separate from the web server. If your site grows beyond a two server "web server" and "database server" configuration then you can consider using a single web server and multiple database servers in a cluster.

Benchmark

One benchmark of a server is MBR.org which required serious intervention for optimisation at roughly the 2m pages per month mark, on a server running Apache1.3 and MySQL 4.1 with 1GB of memory. MySQL indexing, database memory use tweaks and abandoning MyISAM for InnoDB brought it under control - the jury's out on using persistent connections.

There is a need for more case studies like this to be documented on this handbook page

What Drupal.org runs on

As of April 2007 (and for a long time before that) Drupal.org has been running on a group of 3 servers. For details on those servers see Dries post about the "future" drupal.org hardware as it was being delivered.