While I found the WordPress multisite functionality quite easy to setup, I found some pitfalls which I will document here so I won’t tap into them again. It may help other people too.
- Check if your plugins are multisite compatible. I had an issue with YAPB (yet-another-photoblog).
- Install a fresh WP into the root folder of your site (directly into \htdocs).
- When creating new site for each existing site you want to import, you can propably choose the same sub folders as the existing sites. Multisite uses only virtual site addresses (by using URL rewrite rules in .htaccess), so they won’t overwrite your existing installations.
- Before importing, configure the newly created site to match the settings of the existing site to be imported, especially “media” settings. Otherwise thumbnails might stop to work.
- Plugin data will not be imported automatically, if they use custom database tables. Check if your plugins have their own import/export functionalities. If not, you may still be able to manually import the plugin data using phpmyadmin. For the YAPB (yet-another-photoblog) plugin there was just a single table to import.
- Internal links may brake, since Multisite uses different file URLs. You may search/replace links in the import/export XML file.