4 ms·Did that park the heads of the hd before you powered off? I remember doing that in the 80s.by zz865 6y agoDid that park the heads of the hd before you powered off? I remember doing that in the 80s.Gracana 6y agosync flushes the write caches to disk. sync twice makes really damn sure all your files are written to the disk, heh.oilbagz 6y agoNot just disk, also tapes, which is what the original command was for - to sync stuff to the tape spool for offline'ing ..