Lion: Mobile Backup Turn off local Time Machine | Jan-Kaspar Münnich. No idea if I already had this, too lazy to search, but if the local Time Machine backups are annoying (e.g. with smaller SSDs, this is anything but practical, especially if you occasionally perform larger file operations), you can turn them off with tmutil disablelocal and turn them on with tmutil enablelocal. For example, when performing larger cleanup tasks, it makes sense to turn them off, even if you activate them later to have the additional work safety. Or you simply archive everything on the notebook in git or mercurial, then you naturally don't need local backups either.