I've been using Drupal for a long time, and know that it's robust and has tons of features. My question is, is it a framework that you can build REALLY big sites on? And can anyone give some examples of REALLY big sites that have been built with Drupal?
To answer my question about whether or not it's a good idea to build really big sites on Drupal, imagine having to redo facebook as a drupal site. Would it be possible (realistically)?
The Onion and WhiteHouse.gov are Drupal-powered, and I'd say they're fairly huge sites. The founder of the Drupal project keeps a list of some prominent Drupal-powered sites.
imagine having to redo facebook as a drupal site. Would it be possible (realistically)?
Yes but I wouldn't. You should probably define "Big." Do you mean big as in tons of pages or DB storage? Do you mean big as in amount of visitors? Do you mean big as in famous? Drupal is a fine CMS and if scaled properly I'm sure you can handle a large load of visitors. But the main point here is that it is a CMS (with extensibility) and not a good framework for making something completely custom. If you need something truly unique then you should use a real framework like CakePHP or CodeIgnitor, etc.
I went to a conference in London a few months back on the subject. A major UK based charity Comic Relief which has a big TV appeal every 2 years and hit £80million ($100 million) in donations this year. It is run off Drupal, and has a very unique scalability problem in that it only really ets traffic and takes donations on 1 day of the year.
So by using many different database techniques and servers such as reverse proxies it was able to stay working through out the donation day.
It is very possible to make BIG sites on Drupal.
I've been working with drupal for some time now and it's nice, but have in mind that it does a lot for file scanning/including - 80% time spent on bootstrapping I think I heard some where. But in terms of handling lots of traffic it's performing fine.
i've worked on a very big drupal site and there are serious performance problems, even with two db servers and memcache. the site holds up fine, its just not efficient. most likely its the way we've written everything, but even some very talented drupal guys are scratching their heads. bootstrapping is an issue indeed, as is using amfphp
for something like facebook you need a framework, not something that requires 15 additional modules to set up just a blog ...
Go read the blog of, and listen to the podcasts from, Lullabot - they've been involved with some pretty large sites based on Drupal.
One large Drupal user I'm aware of (sorry, don't know if it's a Lullabot site or not) is Sony Music - they're using Drupal 6 to roll out sites for their artists. See Sony Music sponsors major multilingual improvements in Drupal 6 for more.
Essentially, I believe that the ability of Drupal to scale up will be more than 99% of websites ever need. For the other <1% of sites, there are ways to make things faster.
It's a problem I'd like to have. :-)