Where are committed files stored on the SVN server file system?
The SVN repository itself doesn't contain the files in the format that they were committed in.
Instead, the repository's storage uses either FSFS or BDB as storage - most likely for a modern repository, the FSFS format is used.
You probably shouldn't be mucking around much with the files in the repository itself; it's very easy to blow things up, and most cases where you need to work with the repository directly should be handled in the svnadmin command.
If you're just needing the contents of the repository locally on the server, use svn checkout file:///home/svn/repo/.