I don't believe the myth that 'memory_size' should be the size of the uploaded file. The files are definitely not kept in memory... instead uploaded chunks of 1MB each are stored under /var/tmp and later on rebuild under /tmp before moving to the web/user space.
I'm running a linux-box with only 64MB RAM, setting the memory_limit to 16MB and uploading files of sizes about 100MB is no problem at all! Nevertheless, some users reported a problem at a few 100MB, but that's not confirmed... ;-)
The other sizes in php.ini are set to 1GB and the times to 300... maybe the execution_time limits before, since the CPU is just a 233MHz one... :-)
OK,... I got it... finally!
If some of you have also problems uploading large files but the usual sizes/times in php.ini are ok, please check
when you are using session management with your upload script!
The default value is 1440 which is just 24min... so with only 600kbit/s upload rate the session will be closed automatically after uploading
about 100MB. Actually you are able to upload more, but the file won't be copied from the temporary to the destination folder... ;-)
You can set the value also directly inside the php-script via
<?php ini_set("session.gc_maxlifetime","10800"); ?>