varnish

The default installation of Varnish 3 on Debian-based system (including Ubuntu) will set a default timeout for sending files to users (i.e.

If you're using Varnish cache, you will be familiar with the "service varnish restart" then the "oh, there's a config error and now all my sites are down!". Fear no more: there's a command to check your Varnish syntax before you restart. Just run: $ varnishd -Cf /etc/varnish/default.vcl And it will tell you what's wrong (or at least where the error is). If it prints out all your default.vcl, you're good!

I had serious problems with a Drupal website with many Varnish optimizations.

Just a self-reminder, in the vcl_recv section (before sending request to the backend), check the url you want to always serve from cache and tell it to return(lookup);

  if (req.url ~ "request_server.php$") { return(lookup); }

Reload Varnish and get ready for a massive fall of your load if this bloody request_server.php was overloading your site uselessly...