by Mark Matsune.
Thanks very much for taking the time to reply and offer some advice!!!
Actually I just tried that advice I got from the General Help forum and the scheduled automated backups were successfully generated for 9 out of my 15 courses. That's an increase of 5.
In the php.ini file I made the following changes.
changed max_execution_time = 30 to max_execution_time = 300
max_input_time = 60 to max_input_time = 600
The manual zip backups that I generated for the remaining 5 courses range in size from 6 M to 155 M. How much more is it safe to increase the time settings ?
Any advice is greatly appreciated. Thanks in advance.