The document discusses scalability and reverse proxies. It provides information on Pressflow, Varnish, and Nginx as reverse proxy options. It includes configuration examples and optimizations for using Varnish as a reverse proxy with Pressflow to improve scalability and performance.

1. Scalability is the new black

2. 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

3. Pressflow The performance “aware” and scalable fork of Drupal

4. Pressflow Pros Drops support for old PHP versions ( < 5.2 )

5. Better session handling

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

7. Pressflow Cons Less users => less feedback => more unpredictable behavior

8. Delay between corresponding prefflow forks and vanilla Drupal

9. Patch compatibility is not 100% guaranteed

10. Pressflow Should I use Pressflow? Yes

11. if you need the features of PF

12. Pressflow Should I use Pressflow? Yes

13. if you need the features of PF

14. No

15. if you are afraid of experimental and 3 rd party code for the site

16. seixorP esreveR What is it? Α 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.

17. Reverse Proxies Notable examples Apache 2 – with modules

18. Squid – most used proxy

19. Varnish – mostly used with Drupal sites

20. Nginx – http and proxy server in one

21. Varnish Pros Highly recommended from most of the people within the Drupal community

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

23. Surpassed only by nginx with a very small margin