You need to increase the OS support for number of open files.
in linux you can use to view current limit
cat /proc/sys/fs/file-max
Use ulimit to change the number
http://www.cyberciti.biz/faq/linux-increase-the-maximum-number-of-open-files/
Edit: To make limits permenent http://posidev.com/blog/2009/06/04/set-ulimit-parameters-on-ubuntu/