We (leafish) are currently configuring our shiny new dedicated server to host the Drupal sites we produce, and we intend to run all the sites from a single install of Drupal. Everything seems to be working perfectly, but I was wondering if anybody else has tried this on a large (20+ site) scale and run into any problems. I'd prefer to know about any issues now before we commit to this fully.
The server is running CentOS, which is functionally identical to Red Hat Enterprise. We're using Direct Admin to manage our virtual hosting and DNS. I've created two directories for the Drupal code, one for 4.6 and the other is a CVS checkout of the latest head. We're redirecting the customer's public_html directory to one of these two Drupal installations using symbolic links, and creating an entry in the Drupal "sites" directory for each of these to configure database connections and paths. In addition to the custom "modules" and "themes" directories, we're also creating a "files" directory in here for each of the sites to use.
All of this can be automated with scripts, and so far everything is running smoothly. I'd like to hear from anybody who is doing something similar who may be able to advise us on any issues they ran into. So far I'm concerned about redirecting the public_html directly, as this makes it difficult to create any custom directories within each site without configuring Apache. This may also cause similar problems if we want to create a custom .htaccess file. Paul has run into a few issues with paths, which he may comment on if he notices this post.
Thanks for any suggestions.