by Ken Task.
Yeah, there is no admin tool to tell you when a course is getting to large to backup! :\
Have command line access to your server? If so, there is a command line only backup.php script in admin/cli/ that might be able to work ... takes web service out of the loop and is just php talking to your DB and file system then. Uses whatever the defaults are for backup preferences.
Then, however, if that does work, now have the other side of that coin ... can you restore that course backup? No command line script to restore.
However, there is moosh ... which does have a command line restore.
'SoS', Ken