I think it's better to let parted decide how big the partition can be: mkpart primary 0 -1 That should create a partition without a fs type, (no ext3, etc) starting at zero, and using all available. if you have Advanced Format hard drives which are being sold these days, they say you can have performance problems if you start on zero, so you should start at one: mkpart primary 1 -1 Be interesting to know if you see a performance hit either way...