Archiving not working with PHP's disabled functions (no replies)

I have a DirectAdmin server and executed this command a while back:

http://forum.directadmin.com/showthread.php?t=44743

Is it possible to make PHP more secure using the CustomBuild script?
Yes, it is. You need to run "./build secure_php". At the moment it disables some dangerous PHP functions as:
Code:
exec, system, passthru, shell_exec, escapeshellarg, escapeshellcmd, proc_close, proc_open, dl, popen, show_source

Now auto archiving is not working anymore, probably because it uses one of this functions. I can't find which function is being used by Piwik. Does anyone know this?