I know Time Machine makes hourly backups. Since I have a 300GB hard disk, I tought my 500GB external hard drive (wich Im using for backup) would get filled in a day. It doenst, the first backup is of course your whole system, but then Time Machine simply add the upadtes aparantly. How are these updates writen to the disk? I mean, does Time Machine simply ads an upadte folder, or it upadtes the current last backup and keep smaller files for previows "system snapshots"? Im asking this cause I want to delete older backups cause I dont want my externla hard drvie filling up, but I fear "breaking" the backup.