SVN repository structure for Drupal projects

I like to keep all my projects under source control, however big or small. It only takes a few minutes to set up and always saves me time in the long run. When I first started working with Drupal, I spent some time thinking about the best way to SVN-ize my drupal projects and, with the help of several other articles and discussions on the topic (specifically an article from Advantage Labs entitled Advantage Labs SVN Repository Structure and a discussion on workhabbit.org, SVN Repository Structure For Drupal Projects) I settled upon the following structure:

drupal
  sites
    6.x
      all
      site1.com
        modules
        themes
        files
      site2.com
      site3.com
    vendor
      drupal-contrib
        modules
          date
            6.x-2.0-beta3
            6.x-2.x-dev-2008-07-21
            6.x-2.x-dev-2008-07-25
        themes
      drupal-core
        5.7
        6.2
        6.3
      fckeditor
        2.6
        2.6.2
      geshi
      phpmailer

So, to break it down a little:

• /sites/ - Each site has it's own subdirectory in here.
• /sites/all/modules/ - Modules that are used in all sites are pulled in from /drupal/vendor/drupal-contrib/modules with svn:externals. For example:

  svn propedit svn:externals ~/public_html/drupal-6.x/sites/all/modules/
  
  google_analytics    ...drupal-contrib/modules/google_analytics/6.x-1.2
  menu_breadcrumb     ...drupal-contrib/modules/menu_breadcrumb/6.x-1.x-dev
  custom_breadcrumbs  ...drupal-contrib/modules/custom_breadcrumbs/6.x-1.3
  pngfix              ...drupal-contrib/modules/pngfix/6.x-1.0
  pathfilter          ...drupal-contrib/modules/pathfilter/6.x-1.0
  ...
  

  Note: I cut the urls short so they would diplay properly in this article.
• /sites/site1.com/modules - Site specific modules are again pulled in from /drupal/vendor/drupal-contrib/modules with svn:externals.
• /vendor/ - Vendor sources are stored here.
• /vendor/drupal-contrib/modules - Whenever I download a drupal module, I extract it into the appropriate place in this directory. I keep copies of every single version of a module that I have used, including development snapshots.
• /vendor/drupal-core - Each release of drupal gets stored in here. I remove the /sites directory and the robots.txt file first (I use the robotstxt module to dynamically create a unique robots.txt file for each site).

I only need to run two commands to install the whole setup on a new server:

svn checkout /drupal/vendor/drupal-core/6.3 drupal
svn checkout /drupal/sites/6.x drupal/sites

When a new Drupal core is released, I download it, remove the sites directory and robots.txt file and commit it to my repo. Then, I simply run svn switch in my working copy and all sites benefit from the change.

When a new version of a module is released, I download it and commit it to my repository in a suitable location. Then I run svn propedit svn:externals on each of the modules directories that I want to update (or on /sites/all/modules if I want to update for all sites). If the new version of the module causes a problem, I simply change the svn:externals property to point to the old version and svn update again.

I'm sure it could be done better, but it works pretty well for my needs.