I've been using this hack for a while to backup/archive by category:
https://tracker.moodle.org/browse/MDL-20802
but it doesn't seem to be working for me anymore. I'm using version 3.0 ... I can't figure out what I'm doing wrong or if maybe there was a change in code that I'm missing... any ideas?
modify config.php:
$CFG->backup_category = array(65);
modify backup/util/helper/backup_cron_helper.class.php
// Check for categories to backup
if (!empty($CFG->backup_category) && is_array($CFG->backup_category))
{ $rs = $DB->get_recordset_list('course', 'category', $CFG->backup_category); }
else
{ $rs = $DB->get_recordset('course'); }