by Ken Task.
The size of the backup file may not be an indicator of the time and power it requires to make a backup ... as in the case of quizzes.
Try this ... courses can be backed up individually and from command line ... which is like the backup routine as scheduled in autobackups. Look in moodlecode/admin/cli/ for a backup.php script. Help on it:
Perform backup of the given course.
Options:
--courseid=INTEGER Course ID for backup.
--courseshortname=STRING Course shortname for backup.
--destination=STRING Path where to store backup file. If not set the backup
will be stored within the course backup file area.
-h, --help Print out this help.
so to issue:
php backup.php --courseid=# --destination=/someotherlocation/
Choose the largest course you see.
While that is running, open another terminal session (ssh) and go to:
moodledata/temp/backup/
You'll see a long directory name (looks like a contenthash).
cd [longdirectoryname]
Then issue:
watch "ls -lR"
You'll see what Moodle is doing to build a backup.
Pay attention to activities directory and it's contents where the course contains many quizzes.
The above won't solve the problem but it might give some more info upon which one might be able to tweak things that might need tweaking ... thus making the process faster (like running tuner on the DB).
'spirit of sharing', Ken