one update regarding the issue with backup of files larger than 2GB under Windows. Just to make it clear. This problem still persist on Moodle 3.1.2 instance, under Windows 2012 R2, IIS, PHP 5.6.25. At least with the 32 bit PHP version it is not possible to backup Moodle courses larger than 2GB.
Based on the information posted on moodle.org:
"Windows is not suitable for large Moodle installations because PHP for
Windows does not support 64-bit integer numbers, even if it is running
on 64-bit Windows in 64-bit mode. One of the problems is that Moodle may
fail to access data if there are more than 2 billion records in one
database table because the id column is too big for integers. Another
limitation is a maximum file size of 2GB, which can cause problems (for
example) when making backups of large courses. Please consider a
different operating system with full 64-bit support for very large
Due to fact that the PHP 7 ist still not fully tested and supported under Moodle 3.x we have decided to use the PHP 32bit, 5.6.25 version in FastCGI-process under IIS, and PHP 64bit version 7 only in cron backup script. With this configuration we are able to backup courses larger than 2 GB. Unfortunately the limitation persist when we are trying to restore courses which are bigger than 2 GB. The only way to restore them, is to select some activities and materials so that overall there will be less than 2GB of data and conduct the resotration procedure in two, three steps. Hopefully, the next Moodle release will be fully supported by PHP 7 64 bit, and that the backup and restore will work without such problems.