When you are using logstash for centrilized logs workflow there is a time to think how to remove all that old logs to get some space within a server filesystem.
Thanks to the opensource there is a small python program that can help you to get this done easily via crontab, named curator.
For approaching the cleanup tasks you should install curator to your system
As you might know hhvm(HipHop virtual machine) has an ability to be used as fastcgi service for serving php requests.
Currently hhvm is much more faster then php5-fpm or mod_php, so having it as primary php service is a desirable solution.
But there is an issue with hhvm - sometimes this service just fails and kills itself. So it is not an option for production servers.