I read about FHS, and I started to consider the file system of wikipedia. On the one hand, I feel it is a security risk to let everyone know it. On the other hand, it is necessary for developers. For example, is there some rule to know where are all sitemaps and their indices located? So:
How is the file system of Wikipedia designed?
MediaWiki and thus Wikipedia uses MySQL to store all data shown on the site. You can see their database schema here: http://upload.wikimedia.org/wikipedia/commons/4/41/Mediawiki-database-schema.png
The FHS is not specific to Wikipedia or Mediawiki. It's just a suggested way to lay out the filesystems of any *nix-like system.
You could host Mediawiki (the software that runs Wikipedia) on any system that can run PHP and MySQL, regardless of what the underlying filesystem looked like.
Where in that filesystem your MySQL data and indices was stored is going to depend on whether you built MySQL from source or installed a distribution package (in which case it's whereever the package builder decided to put it).
The releasing the file system/database layout would not be much of security issue (security that is worth more than $0.02 works when you how it is done).
Just check out any crypto forum and you will that the security model that they use assumes that the attacker already knows how the system is constructed and which algorithms are in use. The reason is pretty simple, if your security is dependent on keeping the layout secret, than anybody that finds the layout can then break your security. Like the OP said, the people working on the system know the layout (and they don't have jobs for life). Any copies will expose the secret for everyone. In the crypto world, security is based on the idea that without the secret key, every copy must must be broken using methods that are little faster than brute force.
