Afraid the docs are also a little in-correct if one reads this and takes it literally:
'If you leave the field blank, then backup zip files will be saved in the backup folder of each course files folder.'
It appears to suggest the old behavior of <=1.9 ... where moodledata contained course ID folders and had backupdata folder therein.
Moodle 2 no longer uses course ID folders in moodledata folder, but rather, uses the new file system and tags backups with component 'backup' in the DB. Running the following query will show all the .mbz files and their locations in /moodledata/filedir/ deciphering the contenthash
select * from `mdl_files` where `component` like "backup"
Drop down options briefly explained:
* Course Backup filearea - is really /moodledata/filedir/ and in a directory/subdirectory taken from the uniquely generated contenthash.
So backup-moodle2-course-1-mdl24-20130829-1022.mbz
has a content hash of: 204eb4889a4b85c01f68d3b701ddd8ee7b23c1f9
file size of 5706187
is in /moodledata/filedir/20/4e/
and it's name is: 204eb4889a4b85c01f68d3b701ddd8ee7b23c1f9
* Specified Diretory for Automated Backups - is a location on the hard drive or a mount point of a remote file system.
Example: /home/backups/ that directory has to be writable to apache user.
* Course Backup filearea AND the specified directory - means both places
That clear as mud? :\
'spirit of sharing', Ken