Note that the backup function within Moodle is really a "plan C". It doesn't really replace a server backup, which should be done by your server administrator and restores tested when you call a drill, and should include all your Moodle data along with the rest of the server.
That is to say, your Moodle stuff should already be backed up as part of your complete server backup using Clonebox or similar, so the Moodle backup is just extra piece of mind since you should already have a tested daily backup of the whole server.