by Mary Cooch.
Hello Hya - I noticed you had also posted this in the tracker and I replied there:
Sorry for the confusion. For each version of Moodle there is a new version of documentation, so the link you posted is actually for an older version of Moodle - 2.7 (see the URL) If you change the URL to 30 you get the latest documentation which is here: https://docs.moodle.org/30/en/Backup_and_restore_FAQ
The setting was removed in Moodle 2.9 as tgz backups are now standard - see MDL-49298