by Albert Ramsbottom.
I am having similar issue on Moodle 2.6.3
https://moodle.org/mod/forum/discuss.php?d=314226
I have identified that the courses that become unfinished and hand for a few hours each are large courses, between 650mB and 2GB
The odd thing is is the fact that when I watch these courses getting create in the moodle-data/temp/backup directory they dont take a lot of time to get to a certain size (Nearly complete) , but then they just hang for hours, almost like the course backup takes a rest
Cheers