Thread:Project:Support desk/how to share uploads between two MediaWiki servers

We are considering installing MediaWiki. I would like to ask something about how to share uploads between IIS MediaWiki servers. Our environment is: We would like to have more than one IIS MediaWiki servers with the same url. But we do not know how to share the uploads between different IIS MediaWiki servers. It seems $wgUploadDirectory is about this issue, but its value is absolute path, and we cannot make it point to another folder on another server with UNC. If I have something like $wgUploadDirectory = "\\\\10.10.10.35\\w_images"; in LocalSettings.php, there will be error "The upload directory (public) is missing and could not be created by the webserver. ". Anyone can give some hints? Thanks a lot.
 * MediaWiki 1.17
 * PHP 5.38 (IIS 6.0)
 * MySQL: 5.5.15