HOWTO: Setup Multisites with different Databases using CPanel
For those of us who's host uses CPanel, here is a quick guide to get your Drupal installation to support Multisites.
This method allows you to have different domains hosted on one account, and uses different databases to store the content and other settings.
Firstly, some obvious things need to be done.
1. Get your first Drupal site working correctly.
2. Register the additional domain (if using an additional domain as opposed to a sub domain) and get the DNS pointing to your host.
3. Make sure the additional domain has been added to your parked domains in CPanel.
OK, that aside, let's start.
Create the a new Drupal Database
1. Login to your CPanel, and go into "MySql Databases"
2. Create a new database
3. Create a new user
4. Asign appropriate permissions for the new user to the new database
5. Take note of the database and user names INCLUDING ANY PREFIXES that CPanel has probably added.
Create the 'sites' folders
6. Access your Drupal installation via an FTP manager (CPanel's FTP is OK)
7. Create sub folders in the "/sites/" directory which match your new domain name (e.g. www.domainX.com, domainX.com). It is important to note that you need to have both a www prefixed directory, and a non-prefixed directory if you want to support both.
Create the new settings.php files
8. Using FTP, download the "settings.php" file from the "/sites/default" directory
9. Edit the file, changing the "base_url" to your new domain, and the MySQL connection settings
10. Upload the file to your new directories created above in point 7
Check it works
11. Browse to your domain (e.g. http://www.domainx.com) and run the install.php script. At this stage, if you entered the MySQL settings incorrectly, you can type them in again.
OK, well I think that's everything. I'm fairly new to this, so if I've missed anything important, let me know!
David Whitchurch-Bennett
World Wide Wales Web Design a work in progress.....

Point 7 is incorrect
A statement in the above article is incorrect. On point 7, it says,
However, the Drupal documentation at http://drupal.org/getting-started/5/install/multi-site states,
Creating two 'sites' directories to support http://www.example.com and http://example.com is unnecessary and counter-productive as you would need to maintain both directories' settings, modules and themes separately; and assuming you want http://www.example.com and http://example.com to represent the same site (which is usually the case) you run the risk of presenting different settings, modules and themes to users depending on which of these URLs they use when visiting your site.
Using '
sites/example.com/settings.php' (without the 'www') will work for both http://www.example.com and http://example.com ; so if you want to support both forms of URL stick with using just this settings directory.Symlinks maybe necessary
In case it helps anyone else, the above solution didn't work for me until I set up a symlink as described here:
http://drupal.org/node/125539