there are file size limitation options you can upload in /etc/php5/apache2/php.ini file.
In case of ubuntu apache with php5, you can change allowable file size by modifying /etc/php5/apache2/php.ini
; Maximum size of POST data that PHP will accept.
#post_max_size = 8M
post_max_size = 500M
; Maximum allowed size for uploaded files.
#upload_max_filesize = 2M
upload_max_filesize = 500M
# /etc/init.d/apache2 restart
If you upload larger files without modifying above options, you will see the following error.
[error] [client 192.168.122.1] PHP Warning: POST Content-Length of 10486037 bytes exceeds the limit of 8388608 bytes in Unknown on line 0, referer: http://192.168.122.216/upload.html