We are attempting to have our Wikipedia clone website cache files to some local directory, however the write demands towards the directory are now being refused based on the Apache2 error log:

PHP Warning: wfMkdirParents: unsuccessful to mkdir "/var/www/wikipedia/cache/8" mode 511 in /var/www/wikipedia/includes/GlobalFunctions.php online 2179

The cache folder has full read/write/execute permissions for those customers and it is situated within the website's directory, therefore it should not be considered a permissions problem.

Our server is running Ubuntu 10.10 64bit Desktop Edition. Additionally, we're using PHP v. 5.3.3 and Apache v. 2.2.16.