Files ... your moodledata/temp/backup/ - this I think you already know.
DB - Just tables ... have a look at them to assure yourself ... I've included the column info below:
mdl_backup_courses
id bigint(10) No Primary NULL auto_increment
courseid bigint(10) No None 0
laststarttime bigint(10) No None 0
lastendtime bigint(10) No None 0
laststatus varchar(1) No None 5
nextstarttime bigint(10) No None 0
mdl_backup_logs
id bigint(10) No Primary NULL auto_increment
backupid varchar(32) No Indexed
loglevel smallint(4) No None NULL
message longtext No None NULL
timecreated bigint(10) No None NULL
mdl_backup_controllers which logs each backup
id bigint(10) No Primary NULL auto_increment
backupid varchar(32) No None
operation varchar(20) No None backup
type varchar(10) No Indexed
itemid bigint(10) No None NULL
format varchar(20) No None
interactive smallint(4) No None NULL
purpose smallint(4) No None NULL
userid bigint(10) No Indexed NULL
status smallint(4) No None NULL
execution smallint(4) No None NULL
executiontime bigint(10) No None NULL
checksum varchar(32) No None
timecreated bigint(10) No None NULL
timemodified bigint(10) No None NULL
Truncating all of them results in Moodle running autobackups for the first time. So the settings for skip if not modified kinda things won't be known to Moodle and thus included.
With the number of courses you have would check that you have enough space to do this ... I would set preferences to save to an alternative directory (that you must manually create) and not to moodledata/filedir/
This clue: "WHM Cpanel and I think CentOS" indicates your provider might offer attached devices ... data drives. Providers like Rackspace and Google do offer customers such things ... those would have to be mounted by your moodle server and they would show up with a command like:
df -h
Example of a RackSpace box:
main drive ... OS, moodle code, etc:
/dev/xvda1 158G 38G 114G 25% /
attached data devices/drives. First one is Rackspace ... second is a Google Bucket ... note the sizes and how much available ... size, used, available
/dev/xvdb 99G 73G 22G 78% /mnt/data
sossrv 1.0P 0 1.0P 0% /mnt/gbucket
The Google bucket is 1 Pentobyte ... operating system command can't calculate how much is used or available, but I can tell you it will take me a lifetime to fill that up!
Is your entity adverse to using Google? Above is a CentOS 7 server hosted on Rackspace but have access to that Google bucket for backups.
Wouldn't use a Google Bucket for all of moodledata but sure is great for backups!
Amazon has similar/same.
'SoS', Ken